Most cancer screenings don’t extend life, study finds(cnn.com)
cnn.com
Most cancer screenings don’t extend life, study finds
https://www.cnn.com/2023/08/28/health/cancer-screenings-extend-life-wellness/index.html
144 comments
They are conflating cancer survival rates with longevity.
When has someone claimed that treating cancer would increase life expectancy above the average?
This is a dangerous article. People don't need more reasons to avoid cancer screenings.
When has someone claimed that treating cancer would increase life expectancy above the average?
This is a dangerous article. People don't need more reasons to avoid cancer screenings.
It looks like they were comparing a group that got screening vs a group that didn’t get screening. If the group that got screening didn’t live longer than the group that didn’t get screening, that seems like a lot of wasted dollars.
Life expectancy is really only one dimension of "health," and it's probably the most shallow dimension. If I'm quadriplegic and confined to a ventilator but I live to 80, that's the same in this metric as if I'm not paralyzed and able to breathe on my own until I die.
What if some people in the group that didn't get screening had fewer high-quality years? It might simply be that the last 5 years of life for people who are screened positive early on and who subsequently receive treatment is a better 5 years than the last 5 years of life for people who aren't screened positive early on and who subsequently have to undergo brutal hail mary treatments at the last minute.
What if some people in the group that didn't get screening had fewer high-quality years? It might simply be that the last 5 years of life for people who are screened positive early on and who subsequently receive treatment is a better 5 years than the last 5 years of life for people who aren't screened positive early on and who subsequently have to undergo brutal hail mary treatments at the last minute.
> Life expectancy is really only one dimension of "health," and it's probably the most shallow dimension. If I'm quadriplegic and confined to a ventilator but I live to 80, that's the same in this metric as if I'm not paralyzed and able to breathe on my own until I die.
Claiming that there are missing elements that could possibly turn the equation in favor of screening is cause for further research and analysis. You can't just claim that they fall in your favor; some diagnostic and exploratory processes due to false positives are painful and/or dangerous in and of themselves.
> What if
"What if" is right. You can't just conjure these people into existence to justify current policies, you have to find them and do the statistics.
Claiming that there are missing elements that could possibly turn the equation in favor of screening is cause for further research and analysis. You can't just claim that they fall in your favor; some diagnostic and exploratory processes due to false positives are painful and/or dangerous in and of themselves.
> What if
"What if" is right. You can't just conjure these people into existence to justify current policies, you have to find them and do the statistics.
Given that screening is arguably benign for most people, you could argue that we continue screening while we gather more information. But you do whatever you want to do. I'm just pointing out that it's really premature to cancel all of your screenings based on the idea that it doesn't add any years to your life. That may be true, but there's more to a life than how long you live.
> Given that screening is arguably benign for most people
You're 100% wrong here, this is not a given. Prostate cancer screenings, which are very common, can have both false positives as well as findings of cancer that is and would remain completely benign. These can both lead to unnecessary treatments that cause serious negative health effects, including incontinence and erectile dysfunction.
https://www.cdc.gov/cancer/prostate/basic_info/benefits-harm...
You're 100% wrong here, this is not a given. Prostate cancer screenings, which are very common, can have both false positives as well as findings of cancer that is and would remain completely benign. These can both lead to unnecessary treatments that cause serious negative health effects, including incontinence and erectile dysfunction.
https://www.cdc.gov/cancer/prostate/basic_info/benefits-harm...
Also read that death rates from thyroid cancer hasn't changed in 50 years. Despite huge numbers of thyroid screenings and treatment.
An ultrasound of the thyroid often leads to finding a nodule. Which leads to a biopsy. Which comes out indeterminate. Which leads to a thyroidectomy and life long dependence on thyroid hormones.
Another one is ductal carcinoma in situ. Read somewhere there is a 1% chance that will evolve into cancer. And yet you have women having double mastectomies and chemo for it.
An ultrasound of the thyroid often leads to finding a nodule. Which leads to a biopsy. Which comes out indeterminate. Which leads to a thyroidectomy and life long dependence on thyroid hormones.
Another one is ductal carcinoma in situ. Read somewhere there is a 1% chance that will evolve into cancer. And yet you have women having double mastectomies and chemo for it.
Absolutely no one is getting a bilateral mastectomy or chemotherapy for DCIS.
This is by far the most inaccurate medical claim I've ever seen on HN. Where on earth did you get this from?
The whole point of diagnosing DCIS on screening mammography is that it avoids systemic therapy and mastectomy. It also wouldn't be bilateral.
This is by far the most inaccurate medical claim I've ever seen on HN. Where on earth did you get this from?
The whole point of diagnosing DCIS on screening mammography is that it avoids systemic therapy and mastectomy. It also wouldn't be bilateral.
Yes, they do. I have a friend who did just that. Was it justified? I don't know, but it's very real.
So work the numbers. Put together the chance of false positives, false negatives, rate of negative effects from treatment, and rate of death with and without treatment. Tell the patient the risk of each outcome.
The math is easy. If we don't have the numbers for it, then get them. Plenty of people get prostate cancer and some of them choose to just monitor. We should have plenty of information to make a rational decision. This seems preferable to blinding ourselves out of fear that we'll do something stupid with the information we might get.
The math is easy. If we don't have the numbers for it, then get them. Plenty of people get prostate cancer and some of them choose to just monitor. We should have plenty of information to make a rational decision. This seems preferable to blinding ourselves out of fear that we'll do something stupid with the information we might get.
> Tell the patient the risk of each outcome.
This isn't a simple problem of calculating EV. Telling somebody that there's a 40% chance that the positive test is actually wrong and in the 60% case that it's right, 40% of the time it's going to be benign, but if it's not benign it might kill them but if it is benign and they do surgery they might be left wearing diapers is not a simple thing for a person to evaluate. Add to that the fact that people have a bias towards action, so doctors tend to overindex on treatment vs. just ignoring something, and you have an incredibly complex problem.
> The math is easy.
No, it's not. It's a series of probabilities combined with extremely subjective outcomes (getting erectile dysfunction may have a very different impact on your life if you're 40 vs. 80).
> If we don't have the numbers for it, then get them.
You're just trivializing medicine and medical research here. Why don't you just go ahead and build some AI that'll solve this whole problem by diagnosing cancers based on a blood sample? That seems easy enough.
> This seems preferable to blinding ourselves out of fear that we'll do something stupid with the information we might get.
Ironically what you're describing here is the opposite of everything you've just talked about. If we understand the numbers well, and from those we can conclude that tests are highly prone to false positives and thus that treatment based on positive results is more likely to be harmful than helpful, then we shouldn't take those tests. That's not blinding ourselves, it's acting appropriately based on understanding the math.
This isn't a simple problem of calculating EV. Telling somebody that there's a 40% chance that the positive test is actually wrong and in the 60% case that it's right, 40% of the time it's going to be benign, but if it's not benign it might kill them but if it is benign and they do surgery they might be left wearing diapers is not a simple thing for a person to evaluate. Add to that the fact that people have a bias towards action, so doctors tend to overindex on treatment vs. just ignoring something, and you have an incredibly complex problem.
> The math is easy.
No, it's not. It's a series of probabilities combined with extremely subjective outcomes (getting erectile dysfunction may have a very different impact on your life if you're 40 vs. 80).
> If we don't have the numbers for it, then get them.
You're just trivializing medicine and medical research here. Why don't you just go ahead and build some AI that'll solve this whole problem by diagnosing cancers based on a blood sample? That seems easy enough.
> This seems preferable to blinding ourselves out of fear that we'll do something stupid with the information we might get.
Ironically what you're describing here is the opposite of everything you've just talked about. If we understand the numbers well, and from those we can conclude that tests are highly prone to false positives and thus that treatment based on positive results is more likely to be harmful than helpful, then we shouldn't take those tests. That's not blinding ourselves, it's acting appropriately based on understanding the math.
No, I mean you take the test and if it's positive then present options like this:
Risk of death: X% with treatment, Y% without treatment.
Risk of side effect A: X% with treatment, Y% without treatment.
Those numbers take into account the rate of false positives and false negatives. They are clear and understandable.
There are definitely situations in which you shouldn't test: where the rate of the cancer is low, the false positive rate is high, and the risk of treatment is high. In that case, the numbers can show that risk of death is higher with treatment than without, so while (noninvasive) testing doesn't make things worse if we're giving clear numbers, it doesn't help either; we might as well not test at all. But that's not true for everything. As for side effects, we should give patients clear numbers like this so they can make informed decisions.
Adding up the number of false positives and negatives, and the number of patients with various outcomes, is not comparable to using AI.
Risk of death: X% with treatment, Y% without treatment.
Risk of side effect A: X% with treatment, Y% without treatment.
Those numbers take into account the rate of false positives and false negatives. They are clear and understandable.
There are definitely situations in which you shouldn't test: where the rate of the cancer is low, the false positive rate is high, and the risk of treatment is high. In that case, the numbers can show that risk of death is higher with treatment than without, so while (noninvasive) testing doesn't make things worse if we're giving clear numbers, it doesn't help either; we might as well not test at all. But that's not true for everything. As for side effects, we should give patients clear numbers like this so they can make informed decisions.
Adding up the number of false positives and negatives, and the number of patients with various outcomes, is not comparable to using AI.
You are also presented with a choice: you take a test and you die in X% because of the test itself (there are no non-invasive tests, even IV is potentially dangerous), or you may be diagnosed with cancer with Y% chance of right diagnosis and Z% of lethality. Math is getting much more complicated. Now consider that only 2.5% women will die from breast cancer, but 97.5% others will get X-ray exposure once a year (with 100% test coverage of course). X-rays are know to cause mutations and thus cancer. Add to this money spent on tests that can be used to find a cure (we don't have unlimited resources).
Simply having the information that they maybe have cancer, people are not great at just living unstressed because it may or may not be a false positive. And stress is known to cause a lot of problems including weakening immune system.
Which is why you only test in situations where, if the test is positive, you have better odds if you treat.
It’s important to note that it’s not the screening causing those issues. It’s the fact that our health care systems are rather inadequate in properly handling those screening results at the margin.
There is another consideration:
1. You have an aggressive (i.e. non-treatable) cancer, maybe you feel slightly off, but you go on with your life, until you finally got worse and die. Or you performed screening, focus on treatment, bankrupt your family and ... die anyway,
2. You have a slow growing cancer (e.g. prostate), live your life and die of some other causes. Or you performed screening, got surgery, got tons of problems and die of myocardial infarction (yes, that's one of complications after prostate surgery).
If you read the original JAMA publication you would notice that there is a research on quality of life metric. That metric for breast cancer is higher among non-screened women.
1. You have an aggressive (i.e. non-treatable) cancer, maybe you feel slightly off, but you go on with your life, until you finally got worse and die. Or you performed screening, focus on treatment, bankrupt your family and ... die anyway,
2. You have a slow growing cancer (e.g. prostate), live your life and die of some other causes. Or you performed screening, got surgery, got tons of problems and die of myocardial infarction (yes, that's one of complications after prostate surgery).
If you read the original JAMA publication you would notice that there is a research on quality of life metric. That metric for breast cancer is higher among non-screened women.
There are attempts to address this, “The quality-adjusted life year (QALY) is a generic measure of disease burden, including both the quality and the quantity of life lived. It is used in economic evaluation to assess the value of medical interventions.” See: https://en.m.wikipedia.org/wiki/Quality-adjusted_life_year
I'm going to start with one assumption that I believe is true: higher mental and physical stress will kill you faster.
If two statistical people both get cancer, one gets screened and potentially treated, and the other doesn't and they both live to 80, I would rather be the person that doesn't get treated.
A regular schedule of treatments is only better than a hail mary if you actually get more longevity from it, otherwise it's just more pain for the patient. At least with the hail mary, I only spend a short time feeling horrible before dying. This is most likely why doctors don't opt for treatment more than the average.
https://slatestarcodex.com/2013/07/17/who-by-very-slow-decay...
If two statistical people both get cancer, one gets screened and potentially treated, and the other doesn't and they both live to 80, I would rather be the person that doesn't get treated.
A regular schedule of treatments is only better than a hail mary if you actually get more longevity from it, otherwise it's just more pain for the patient. At least with the hail mary, I only spend a short time feeling horrible before dying. This is most likely why doctors don't opt for treatment more than the average.
https://slatestarcodex.com/2013/07/17/who-by-very-slow-decay...
Yes but as someone else mentioned, it's like an insurance policy. Buying insurance doesn't make you richer on average, it makes the insurance company richer. But you aren't guaranteed the average outcome, so it's still rational to get the insurance, to cover the cases where you'd otherwise have a catastrophic loss. As with gambling, it's not just about expected value. You also have to consider risk of ruin.
False positives can be debilitating or fatal.
But at what rate? The study doesn't say.
FTA: "Overall cancer mortality worldwide has decreased significantly, falling 33% since 1991, in part due to early detection as well as advances in treatment and declines in smoking."
I think the consensus on cancer screening is stil not fully there? Came across this video by a cardiologist a long time ago
https://youtu.be/yNzQ_sLGIuA?si=fUttSVFQjsrIqc-p
I guess the main gist is that screening is not completely benign and a positive screen might lead to more interventions for what in the end could just be a benign tumor. Then there's the other point of detecting it late in life. Like treatment for cancer might not make much sense if you are already 89 years old
https://youtu.be/yNzQ_sLGIuA?si=fUttSVFQjsrIqc-p
I guess the main gist is that screening is not completely benign and a positive screen might lead to more interventions for what in the end could just be a benign tumor. Then there's the other point of detecting it late in life. Like treatment for cancer might not make much sense if you are already 89 years old
This is the negative expectation part of most medical screening that most analyses miss.
- Medical screenings themselves have iatrogenic effects,
- the false positives interventions resulting from screenings have further negative effects and
- finally the true positive interventions don't necessarily prolong life.
All in all very difficult (confounding) tradeoffs that are impossible to quantify and understand especially when the cultural pressure is to do something.
- Medical screenings themselves have iatrogenic effects,
- the false positives interventions resulting from screenings have further negative effects and
- finally the true positive interventions don't necessarily prolong life.
All in all very difficult (confounding) tradeoffs that are impossible to quantify and understand especially when the cultural pressure is to do something.
Do you really believe your third point? That most medical interventions for cancer do not prolong life? Or the word necessarily means your argument is null like "not all interventions prolong life". Yeah , we knew that already. It's never 100%.
Sorry for the delay in responding.
I actually do and most of it based on what I have have directly experienced with what, especially older doctors, counsel their patients.
There is a lot of literature on how doctors die [1], which also drives my beliefs.
I am also influenced and how weak the statistical significance is on evidence based literature on interventions and how often the interventions are difficult to replicate.
As always, please do your own research :)
1- https://www.thehappymd.com/blog/bid/295228/how-doctors-die
I actually do and most of it based on what I have have directly experienced with what, especially older doctors, counsel their patients.
There is a lot of literature on how doctors die [1], which also drives my beliefs.
I am also influenced and how weak the statistical significance is on evidence based literature on interventions and how often the interventions are difficult to replicate.
As always, please do your own research :)
1- https://www.thehappymd.com/blog/bid/295228/how-doctors-die
> most medical interventions for cancer do not prolong life
Specifically, medical interventions for cancer AS A RESULT of some types of screening do not prolong life.
Medical interventions for symptomatic cancer, and some types of screening, certainly do prolong life, and quality of life.
There are so many confounding factors in this it's hard to do something like a pareto breakdown, but it would certainly be interesting to see.
Specifically, medical interventions for cancer AS A RESULT of some types of screening do not prolong life.
Medical interventions for symptomatic cancer, and some types of screening, certainly do prolong life, and quality of life.
There are so many confounding factors in this it's hard to do something like a pareto breakdown, but it would certainly be interesting to see.
I'd rather die of cancer than die of chemotherapy.
A friend of mine had a pretty agressive cancer at age 16. He suffered through chemotherapy, a bone marrow transplant, and another round of chemo a year later. I think it sucked pretty bad. I visited him once in hospital, they made me wear a full body suit to prevent any infections.
But that was 20 years ago. He lives a normal life now and has a family. I'm pretty sure chemo was worth it.
But that was 20 years ago. He lives a normal life now and has a family. I'm pretty sure chemo was worth it.
Why would it be dangerous for people to avoid cancer screenings if those screenings do not impact life expectancy? You might want to know if you have cancer, but doesn't this suggest that...there's no baseline argument to suggest that all people undergo those screenings?
They do impact life expectancy. The English language is a bit confusing to some mixed with statistics. They do not make life greater than average but they do make you closer to the average than if you die earlier.
If we decrease premature deaths from any cause, particularly a common cause of premature deaths, we increase life expectancy. Or just what do the authors think life expectancy means? It's an average. Every premature death drags down average life expectancy.
If we say that cancer screening has no effect of life expectancy, that's exactly the same as saying that it doesn't prevent premature deaths.
If cancer screening effectively prevents premature deaths, but the effect on the population's life expectancy is small, that effect is the wrong thing to be focusing on, potentially resulting in a harmful takeaway message.
If we say that cancer screening has no effect of life expectancy, that's exactly the same as saying that it doesn't prevent premature deaths.
If cancer screening effectively prevents premature deaths, but the effect on the population's life expectancy is small, that effect is the wrong thing to be focusing on, potentially resulting in a harmful takeaway message.
No, because we might be replacing one cause with another.
That's what they've found with PSA--it kills (via treating things that wouldn't actually have killed the patient) as many as it saves.
That's what they've found with PSA--it kills (via treating things that wouldn't actually have killed the patient) as many as it saves.
> That's what they've found with PSA--it kills (via treating things ...)
I'm not sure what PSA you're referring to. The Prostate-Specific Antigen PSA is something secreted by the body, and not a treatment, so it can't be that one.
Are you referring to overdiagnosis (via PSA or any other screening), resulting in overtreatment?
I'm not sure what PSA you're referring to. The Prostate-Specific Antigen PSA is something secreted by the body, and not a treatment, so it can't be that one.
Are you referring to overdiagnosis (via PSA or any other screening), resulting in overtreatment?
PSA is also commonly used to refer to the test that measures the PSA level.
And, yes, it's treatment of things that weren't actually going to kill the patient. It's been known for quite a while that doing the test for screening produces no increase in life expectancy.
What this study is saying is that the same problem seems to apply to most other cancer screenings.
And, yes, it's treatment of things that weren't actually going to kill the patient. It's been known for quite a while that doing the test for screening produces no increase in life expectancy.
What this study is saying is that the same problem seems to apply to most other cancer screenings.
You may be decreasing premature deaths from cancer but increasing premature deaths from other causes related to screening, thus you don't increase life expectancy. Read the original article in JAMA.
There's only two things that are certain in this world, death and taxes - Benjamin Franklin.
The main purpose of screening for early disease or genetic condition detection regardless of the diseases or illness, cancer, heart attack, stroke, etc, is not really to prolong longevity, even though that's a wonderful side effect, but the main thing to prevent complication(s) that may arise from the late detection.
Apparently death does not incurs extra and massive medical bills, on the other hand complications will certainly do. If you connect the dots, this suddenly become a really good and plausible conspiracy theory.
It's a shame that most of the health organizations, I'm looking at you American Heart Association (AHA), are really against any form of routine screening [1],[2].
[1] American Heart Association 14-Element Screening (Maron, BJ Circulation 2014):
https://med.stanford.edu/content/dam/sm/ppc/documents/HSuper...
[2] ACC/AHA Release Recommendations For Congenital and Genetic Heart Disease Screenings in Youth:
https://www.acc.org/latest-in-cardiology/articles/2014/09/15...
The main purpose of screening for early disease or genetic condition detection regardless of the diseases or illness, cancer, heart attack, stroke, etc, is not really to prolong longevity, even though that's a wonderful side effect, but the main thing to prevent complication(s) that may arise from the late detection.
Apparently death does not incurs extra and massive medical bills, on the other hand complications will certainly do. If you connect the dots, this suddenly become a really good and plausible conspiracy theory.
It's a shame that most of the health organizations, I'm looking at you American Heart Association (AHA), are really against any form of routine screening [1],[2].
[1] American Heart Association 14-Element Screening (Maron, BJ Circulation 2014):
https://med.stanford.edu/content/dam/sm/ppc/documents/HSuper...
[2] ACC/AHA Release Recommendations For Congenital and Genetic Heart Disease Screenings in Youth:
https://www.acc.org/latest-in-cardiology/articles/2014/09/15...
Just curious, have you read the original article in JAMA?
The paper [1] is more well written and clear than the CNN article. They were comparing the aggregate life expectancies of people who went through regular screenings vs those who did not, and there was near zero difference except for colorectal screenings where the difference was about 4 months of difference.
The paper is indeed presenting strong evidence that regular screenings have minimal value.
[1] - https://jamanetwork.com/journals/jamainternalmedicine/fullar...
The paper is indeed presenting strong evidence that regular screenings have minimal value.
[1] - https://jamanetwork.com/journals/jamainternalmedicine/fullar...
I can confirm these findings. My father, aged 63, passed away just 3 days ago because of blood cancer. He was totally fit and fine until 8 months ago when we first noticed his abnormal blood counts.
He did regular screening, nothing came up in it. When suddenly in one blood report, his counts were low that's when we did some extensive testing. Even with extensive testing, the diagnosis kept changing. From Myelofibrosis to MDS to AML to AEL.
Whole aspects around testing and related studies are very confusing. Tests are not at all accurate and testing is very expensive.
It seems like a scam when it comes to testing industry and pharma industry for such disorders. Bottomline is nothing helped in my father's case and we lost him after spending tons of money.
The fact that medical system remains such an inefficient system till date indicates to me that world leaders doesn't want to solve for health problems. It's an industry for them with lots of money. Everyone seems to be motivated to keep population seek and be subscribed to their drugs.
Sorry for the rant.
He did regular screening, nothing came up in it. When suddenly in one blood report, his counts were low that's when we did some extensive testing. Even with extensive testing, the diagnosis kept changing. From Myelofibrosis to MDS to AML to AEL.
Whole aspects around testing and related studies are very confusing. Tests are not at all accurate and testing is very expensive.
It seems like a scam when it comes to testing industry and pharma industry for such disorders. Bottomline is nothing helped in my father's case and we lost him after spending tons of money.
The fact that medical system remains such an inefficient system till date indicates to me that world leaders doesn't want to solve for health problems. It's an industry for them with lots of money. Everyone seems to be motivated to keep population seek and be subscribed to their drugs.
Sorry for the rant.
> except for colorectal screenings where the difference was about 4 months of difference
That sounds, uh, significant. So to clarify, does that mean people gain 4 months on average by getting this screening? Those who get the cancer gain years, and those that don't gain 0, so the average is 4 months?
That sounds, uh, significant. So to clarify, does that mean people gain 4 months on average by getting this screening? Those who get the cancer gain years, and those that don't gain 0, so the average is 4 months?
That is how I read it.
It also makes me wonder that if some cancers are rare enough to average to 0 months (rounded down) that could still work out to a 1/500 chance of living to 80 vs 40. Long odds it matters, but big difference if it does.
It also makes me wonder that if some cancers are rare enough to average to 0 months (rounded down) that could still work out to a 1/500 chance of living to 80 vs 40. Long odds it matters, but big difference if it does.
They were testing for some of the most frequent cancers (breast, colorectal, lung cancer (in smokers), prostate), and measuring differences in outcomes down to the day.
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Think of what you're saying. If it was so bimodal that the screened people "gained years" while the ones who didn't "gained 0", then how could the average possibly be 4 months?
If we take your theory at face value, on average the screened people would have an 8 month increase.
If we take your theory at face value, on average the screened people would have an 8 month increase.
A very simplistic hypothetical scenario could be, people who get colon cancer die an average of 6-7 years earlier than they would have. And if 5% of the population get colon cancer, then the average gain would be 4 months with screening.
Thanks for posting that. I read the article but not the paper, but I still feel like this may be a case where scientists "treat all time equally" in a way that most people do not, resulting in differing conclusions even though the data is the same.
That is, putting aside monetary costs for the moment (which I know is not a good idea in reality, but want to focus on another issue), you often hear about how false positives cause "added anxiety and unnecessary treatments, which can cause harm", but if a breast cancer screening saves, say, lets one woman live until 80 instead of dying at 40, how many other people's "added anxiety" would it take to say "OK, that test was worth it". I think a lot of folks would go think that saving that life should be valued a lot more than just, say, comparing 40 years for her vs. time/anxiety "wasted" for false positives.
That is, putting aside monetary costs for the moment (which I know is not a good idea in reality, but want to focus on another issue), you often hear about how false positives cause "added anxiety and unnecessary treatments, which can cause harm", but if a breast cancer screening saves, say, lets one woman live until 80 instead of dying at 40, how many other people's "added anxiety" would it take to say "OK, that test was worth it". I think a lot of folks would go think that saving that life should be valued a lot more than just, say, comparing 40 years for her vs. time/anxiety "wasted" for false positives.
X-ray is not just adding anxiety, it's harmful, and it's affecting all women who get screening, not only those who actually get cancer. Magic of numbers.
If we are avoiding premature deaths for a subset of the population, wouldn't that by definition increase average life expectancy?
Then the way this is being divulged is absolutely a very bad way
Yes, life expectancy should count premature deaths
Saying it "doesn't extend live" goes against that, because it absolutely does increase life expectancy
Science communication is bad
Yes, life expectancy should count premature deaths
Saying it "doesn't extend live" goes against that, because it absolutely does increase life expectancy
Science communication is bad
So they increase your lifespan probabilistically, but not in any terms you can measure. That said, the article's points about the costs of screening is valid and interesting. False negatives, false positives, time and money, those are absolutely real costs and worth taking into account.
Have you read the original article, not the CNN interpretation? They are talking about harm vs benefits of screening. In simple words: you performed colonoscopy, got colon perforation and died of complications. Was colon cancer prevented? Absolutely! You didn't die of colon cancer! Is it any easier? No, it's not. The chance of dying of breast cancer is around 2.5%, so 1 women in 39 will die from that. OTOH annual X-rays affect the other 38 too, how many of them will die from X-ray exposure (which can cause e.g. another type of cancer, not necessary breast)? For the sake of discussion let's say 1 in 380. Congratulations, you've just increased breast cancer related death by 10%! Only it won't be in statistic as deaths from breast cancer.
I mean, you could interpret that as "most cancer screenings don't extend life, because they come back negative". It's the "not most" case you're testing for in the first place.
Not all positive tests are cancer. In some cases, actual cancers could be a tiny minority of positive tests. The tests themselves are a dangerous tool, and the way we minimize that danger is through statistics.
Then you are just changing one form of bad communication with another form. When a test indicates that there is cancer, the physician is not supposed to say "you have cancer" but rather "there is X% probability that you have cancer." If the test comes back negative, it should be "there is Y% probability that you have cancer" where presumably Y<X.
I am skeptical of the implied lesson of this analysis—and it is a meta-analysis of other research, not an original study.
Just take as given that the analysis is correct, and screening for rare Disease A on net has no effect on life expectancy. Almost no one actually gets Disease A, but everyone is screened for it, and that has some diffuse cost to life expectancy: Screen enough people enough times and someone will die in a car accident on the way to or from the doctor's office. More likely the screening crowds out other more net-beneficial medical testing or is taken as some false comfort to continue an unhealthy lifestyle.
Modern cancer treatment, especially for the most common types (i.e. the most likely to be screened for) is very good, even if the cancer is caught later due to lack of screening. So even the folks who catch it early due to screening don't incur a benefit in many cases, further pushing down the life-expectancy win on average.
Still: This is like saying home insurance is a bad deal because on average the insurance companies make money. Screening is an insurance policy (not a free one, to be sure) against a catastrophic outcome.
If you're a public health authority in a utilitarian and budget-constrained mindset, sure, don't encourage screenings by the logic and findings of this analysis. But I don't think individuals should consider on-average-LE-negative screenings as something to avoid.
Just take as given that the analysis is correct, and screening for rare Disease A on net has no effect on life expectancy. Almost no one actually gets Disease A, but everyone is screened for it, and that has some diffuse cost to life expectancy: Screen enough people enough times and someone will die in a car accident on the way to or from the doctor's office. More likely the screening crowds out other more net-beneficial medical testing or is taken as some false comfort to continue an unhealthy lifestyle.
Modern cancer treatment, especially for the most common types (i.e. the most likely to be screened for) is very good, even if the cancer is caught later due to lack of screening. So even the folks who catch it early due to screening don't incur a benefit in many cases, further pushing down the life-expectancy win on average.
Still: This is like saying home insurance is a bad deal because on average the insurance companies make money. Screening is an insurance policy (not a free one, to be sure) against a catastrophic outcome.
If you're a public health authority in a utilitarian and budget-constrained mindset, sure, don't encourage screenings by the logic and findings of this analysis. But I don't think individuals should consider on-average-LE-negative screenings as something to avoid.
There's an amazing mathematical paradox, maybe even better than the birthday paradox, related to screening for rare diseases, that dramatically changes the formula. Imagine there's some terrible disease affects 1 in 1 million people. And there's a test that's 99% accurate. You go get screened for the disease, and it comes up positive. Oh no! What are the chances that it was a false positive? Intuition would tell you 1%. In reality? It's 99.99% likely to be a false positive.
Why? Imagine 1 million people get tested. Well we know exactly 1 person (on average) in that group is going to have the disease. But our 99% accurate test will ring a positive 1%, or 10,000 times. So the odds that you really have the disease are the odds that you're that 1 in 10,000 which is 99.99% against! Well just run the test again. Oh no! It turns up positive again! What are the odds it's two false positives? 99%! Same math. Now we know that 1 person has the disease, but our test will show 1%, 100 people, in the 10,000 as being positive. So your odds of having it are 1 in 100, or 99% against.
I'm not especially interested in being tested for rare conditions.
Why? Imagine 1 million people get tested. Well we know exactly 1 person (on average) in that group is going to have the disease. But our 99% accurate test will ring a positive 1%, or 10,000 times. So the odds that you really have the disease are the odds that you're that 1 in 10,000 which is 99.99% against! Well just run the test again. Oh no! It turns up positive again! What are the odds it's two false positives? 99%! Same math. Now we know that 1 person has the disease, but our test will show 1%, 100 people, in the 10,000 as being positive. So your odds of having it are 1 in 100, or 99% against.
I'm not especially interested in being tested for rare conditions.
Aye that’s a great one. Even testing and treating not so rare conditions can lead to statements that seem different when you know the details.
Imagine you test early and often for a condition in country A much more often than country B which waits until some more late stage easier to detect symptoms occur. Now compare survivor rates. Much higher in country A! We should clearly also be testing in country B, right?
Depends. If the condition is something that doesn’t often actually kill and typically remains at a non lethal but detectable state then all you might have done is treat a lot of extra non fatal conditions that usually only is detected in country B once it evolves to a more advanced and dangerous state. You may have put many people in country A through an unnecessary, expensive, and frightening treatment regime.
The point is that these things are complex and need thorough analysis.
Imagine you test early and often for a condition in country A much more often than country B which waits until some more late stage easier to detect symptoms occur. Now compare survivor rates. Much higher in country A! We should clearly also be testing in country B, right?
Depends. If the condition is something that doesn’t often actually kill and typically remains at a non lethal but detectable state then all you might have done is treat a lot of extra non fatal conditions that usually only is detected in country B once it evolves to a more advanced and dangerous state. You may have put many people in country A through an unnecessary, expensive, and frightening treatment regime.
The point is that these things are complex and need thorough analysis.
> Still: This is like saying home insurance is a bad deal because on average the insurance companies make money. Screening is an insurance policy (not a free one, to be sure) against a catastrophic outcome.
I'd say this depends on the nature of the diffuse negative effects you mention - if it's car accidents on the way to the doctor's office that's one thing, but if it's people dying during surgery they actually didn't need that's another
I'd say this depends on the nature of the diffuse negative effects you mention - if it's car accidents on the way to the doctor's office that's one thing, but if it's people dying during surgery they actually didn't need that's another
The article quotes some one saying this isnt a call to abandon screenings in totality.
The risks are not 'car crash from doctors visit' they are 'got cancer from imaging', 'unnecessary surgery and complications', etc - the risks are directly related to the screening.
This is an active topic in medical ethics as well which you seem ignored of (no offense intended), given that you are framing this in terms of insurance or public health from the perspective of a beaurocrat - the bottom line is that if your screening is more likely to kill or maim you than the thing being screened for then that screening shouldn't be standard practice, and when it is less clear cut than that you still have to make a determination about which screenings make sense to perform on a population level.
That is something that a caring doctor has to think about as part of their duty, there is the very real potential to do much more harm than good by being thoughtless about the interventions you perform.
The risks are not 'car crash from doctors visit' they are 'got cancer from imaging', 'unnecessary surgery and complications', etc - the risks are directly related to the screening.
This is an active topic in medical ethics as well which you seem ignored of (no offense intended), given that you are framing this in terms of insurance or public health from the perspective of a beaurocrat - the bottom line is that if your screening is more likely to kill or maim you than the thing being screened for then that screening shouldn't be standard practice, and when it is less clear cut than that you still have to make a determination about which screenings make sense to perform on a population level.
That is something that a caring doctor has to think about as part of their duty, there is the very real potential to do much more harm than good by being thoughtless about the interventions you perform.
I’m not arguing that all screenings are worthwhile, or that the questions you raise aren’t vital to answer for good medical practice.
I’m arguing that this specific analysis has very little to tell individuals about how they should perceive the value of any particular test. A different analysis—looking at the particular negative outcomes of the testing itself or the reaction to false positives—would be a different story entirely.
What do you think the individual patient should take away from this analysis in actionable terms?
I’m arguing that this specific analysis has very little to tell individuals about how they should perceive the value of any particular test. A different analysis—looking at the particular negative outcomes of the testing itself or the reaction to false positives—would be a different story entirely.
What do you think the individual patient should take away from this analysis in actionable terms?
I see! Who are you arguing against? The article gives zero indication that any of this is actionable, seems to advocate not changing anything with respect to your regular medical care.
But to answer your question; 'nothing'. This is interesting but it isn't actionable.
But to answer your question; 'nothing'. This is interesting but it isn't actionable.
I thought the article was pretty sloppy in its description of the results. Here’s the lede:
Most cancer screenings don’t ultimately give someone extra time beyond their regular lifespan, according to a new review of clinical trials involving more than 2.1 million people who had six kinds of common tests for cancer.
This is trivially misreadable as “an individual with cancer who catches it early via screening doesn’t see appreciable lifespan benefits”, which is decidedly not what the analysis purports to show.
The use of “someone” makes me question whether the author of the CNN article understood the analysis in the first place. The phrase “extra time” is also particularly strange, since it’s something of a loaded term in the world of serious disease. I don’t get a cancer screening because I want “extra time”. I look to get on the early-access list for an unapproved chemo drug because I want “extra time”. The article goes on to frame the results in a way that easily could be misunderstood to be the benefits for sick patients to early detection rather than the average benefits across the entire population, sick and healthy.
Most cancer screenings don’t ultimately give someone extra time beyond their regular lifespan, according to a new review of clinical trials involving more than 2.1 million people who had six kinds of common tests for cancer.
This is trivially misreadable as “an individual with cancer who catches it early via screening doesn’t see appreciable lifespan benefits”, which is decidedly not what the analysis purports to show.
The use of “someone” makes me question whether the author of the CNN article understood the analysis in the first place. The phrase “extra time” is also particularly strange, since it’s something of a loaded term in the world of serious disease. I don’t get a cancer screening because I want “extra time”. I look to get on the early-access list for an unapproved chemo drug because I want “extra time”. The article goes on to frame the results in a way that easily could be misunderstood to be the benefits for sick patients to early detection rather than the average benefits across the entire population, sick and healthy.
If you add "on average" that's exactly what the original paper says. The averaging is over "someone who doesn't get cancer but died of screening complications", "someone who got false positive and decreased their lifespan with unnecessary treatments", and of course "someone who got true positive and increased his lifespan due to treatment". Are you sure you will be in the last group?
Ok, you've convinced me. This article could have given more information and context so that folk without that benefit would walk away with a more nuanced understanding of screening and its seemingly paradoxical costs. A short article that glosses over the details was not appropriate for this subject. Seeing plenty of evidence for that in this comment section.
I agree with your meta-analysis-analysis completely. Just chiming in to say that I chuckled when you reminded me of this classic: https://twitter.com/dril/status/464802196060917762?lang=en
what are some cancer screening that one should actively pursue?
Speak with your doctor about this, especially because I am not one, but from what I understand, the ones that you have a family history for, are pre-diposed by environment, the common ones, and the ones caught by usual body checks / tests during check ups. Again, not giving advice but things you can start a conversation with your doctor with.
The other comment basically got it. Ask doctor particularly with family history. All cancers are better treated if caught earlier but some like colorectal cancer have much less severe outcomes if caught early on (eg removing a large segment of colon vs a small polyp)
(Note: very US centric comment here) I’ve become skeptical of the motives behind any article that seems to seed some level of doubt about health screenings and any preventative or treatment measure that involves the healthcare system itself. They always stink of the insurance and for-profit healthcare system and their aversion to paying anything out beyond the absolute bare minimum to get people the care they need. I often wonder how different public attitudes would be towards treatment and prevention if the US healthcare system wasn’t profit driven.
Ya exactly, I’ve had 2 family members catch pancreatic cancer early and be cured. It’s typically the most fatal cancer.
This study did not look at pancreatic cancer.
I can see why insurance companies might not want to pay, but the people selling the screenings absolutely would want you to get screened.
I dunno about all types of cancer (and screening methods), but mammograms definitely are not helpful and this has been known for a long time [0]
[0] https://www.vox.com/2015/7/6/8900751/breast-cancer-overdiagn... (2015)
I dunno about all types of cancer (and screening methods), but mammograms definitely are not helpful and this has been known for a long time [0]
[0] https://www.vox.com/2015/7/6/8900751/breast-cancer-overdiagn... (2015)
> I often wonder how different public attitudes would be towards treatment and prevention if the US healthcare system wasn’t profit driven.
i seem to also remember seeing they offer incentives like first screening only 700 yen (about 5 bucks) etc
so, yea, different systems, different incentives i guess
In Europe, screenings generally aren't a thing unless you're in some risk group. It's not deemed to be effective enough and staff already have a bunch of actually sick people to treat
Only the author of the paper is from Europe?
An excellent episode of EconTalk came out today on this very subject:
Open: https://simplecast.econtalk.org/episodes/vinay-prasad-on-can...
Apple: https://podcasts.apple.com/us/podcast/econtalk/id135066958?i...
Highly recommend the episode and show. The gist is that cancer is only 4% of deaths, and screening only reduces those 4% by 20% (so it does not help whatsoever 80% of cancers). But there is a lot more to the episode.
The most important thing you need to do to prevent early death is reduce heart attack and stroke, and that requires better diet and exercise. Really the best drug of all is diet and exercise.
Open: https://simplecast.econtalk.org/episodes/vinay-prasad-on-can...
Apple: https://podcasts.apple.com/us/podcast/econtalk/id135066958?i...
Highly recommend the episode and show. The gist is that cancer is only 4% of deaths, and screening only reduces those 4% by 20% (so it does not help whatsoever 80% of cancers). But there is a lot more to the episode.
The most important thing you need to do to prevent early death is reduce heart attack and stroke, and that requires better diet and exercise. Really the best drug of all is diet and exercise.
Those numbers seem really off. The US has 3,464,231 deaths per year with cancer killing just over 600k, so 17.3%. https://www.cdc.gov/nchs/fastats/deaths.htm https://www.cancer.org/research/cancer-facts-statistics/all-...
Also cancer screenings happen in the US. Thus 750k deaths without screenings and 80% of that = 600k deaths with screenings and 150k deaths postponed.
Are they using some unusual definition or something?
Also cancer screenings happen in the US. Thus 750k deaths without screenings and 80% of that = 600k deaths with screenings and 150k deaths postponed.
Are they using some unusual definition or something?
The 4% GP quoted was in reference to individual cancers (since there is no "cancer" screening, each screening is specific to a type of cancer).
I'm having trouble finding numbers, but the comment by Vinay was basically saying that each screening is testing for something that has 1-4% chance of killing you. Not that 4% of all cause mortality is cancer, which is incorrect. In the context of individual screenings per cancer, the numbers roughly make sense based on what I could find, but I am by no means an expert.
The specific video/content they are rehashing is the one by Vinay here - https://www.youtube.com/watch?v=-9hQO7X1bmU
I'd highly recommend listening to the Econtalk conversation as there is a lot of nuance behind why screenings (at least as they are done today) could potentially be a net negative at the individual level and don't seem to have improved all-cause mortality in a significant way (according to Vinay).
I'm having trouble finding numbers, but the comment by Vinay was basically saying that each screening is testing for something that has 1-4% chance of killing you. Not that 4% of all cause mortality is cancer, which is incorrect. In the context of individual screenings per cancer, the numbers roughly make sense based on what I could find, but I am by no means an expert.
The specific video/content they are rehashing is the one by Vinay here - https://www.youtube.com/watch?v=-9hQO7X1bmU
I'd highly recommend listening to the Econtalk conversation as there is a lot of nuance behind why screenings (at least as they are done today) could potentially be a net negative at the individual level and don't seem to have improved all-cause mortality in a significant way (according to Vinay).
There are also plenty of screening tests that catch multiple kinds of cancers. But focusing on individual tests misses the forest for the trees. Sure when you look at ever smaller subsets the benefits can seem smaller in each subset, however that’s directly offset by there being more groups.
Critically, these studies are backward looking they can tell you want taking such a test in 2017 followed by getting treatment in 2017 might do, but that doesn’t directly translate to what taking a test in 2024 would be worth.
As to changing all-cause mortality, when you’re talking 8 billion people even moving the needle by a single day represents another 5 years for 4 million people. That’s a big deal.
Treatments for the young tend to move the needle more because the young are likely to live longer. However in the developed world we’ve mostly plucked the low hanging fruit. That’s more or less the definition of a developed country, the obvious routes for development have already happened.
Critically, these studies are backward looking they can tell you want taking such a test in 2017 followed by getting treatment in 2017 might do, but that doesn’t directly translate to what taking a test in 2024 would be worth.
As to changing all-cause mortality, when you’re talking 8 billion people even moving the needle by a single day represents another 5 years for 4 million people. That’s a big deal.
Treatments for the young tend to move the needle more because the young are likely to live longer. However in the developed world we’ve mostly plucked the low hanging fruit. That’s more or less the definition of a developed country, the obvious routes for development have already happened.
Exercise also reduces cancer risk.
That 4% number is extremely wrong. Either you or the podcast has a misunderstanding. Though I guess it is EconTalk, not MedTalk.
The actual study is (after some URL sanitization):
https://jamanetwork.com/journals/jamainternalmedicine/fullar...
and I do not like it. It suffers from what I consider an extremely common problem in statistics: if you define the question poorly, then your output is garbage no matter how fancy or careful your analysis is.
We can start with the beginning of the abstract:
> Importance Cancer screening tests are promoted to save life by increasing longevity, but it is unknown whether people will live longer with commonly used cancer screening tests.
I have never heard of a doctor suggesting a cancer screening by saying "this might save your life by increasing your longevity." What does that even mean?
So let's try to figure it out. The paper uses the terms "lifetime" and "longevity" somewhat interchangeably, and it does not define either term. The best I can figure out is that, for an individual deceased person, they have a certain lifetime in days from when they were screened to when they because deceased. (Or a certain lifetime in days from birth to death, and I'm not sure this distinction matters.)
Great, but this is only for one patient. What about for a sample of patients or for a population in general or for the probability distribution of lifetimes of a given patient conditioned on whether they do or do not get screened? The article does not say, and a single "lifetime" number is not a probability distribution. Is it an expected value or a mean? A median? A mode? No comment.
One of the headline conclusions is:
> Based on the observed relative risks for all-cause mortality and the reported follow-up time in the trials, the only screening test that significantly increased longevity was sigmoidoscopy, by 110 days (95% CI, 0-274 days) (Table 2, Figure 2)
Figure 2 is useless. Table 2 is somewhat informative, and it has a column for relative risk of all-cause mortality and a column for lifetime gained and its 95% CI. But WAIT A MOMENT! The only way you can know the lifetime of an individual patient is if they're dead. If they're dead, their risk of all-cause mortality by the time they died is 100%. That's not 100% plus or minus something with some relative risk thrown in -- they are dead enough to have a date of death so that someone could compute their lifetime! Or maybe "lifetime" means something else, and the authors didn't bother to figure it out and say what they meant. So what exactly is this paper even analyzing?
So I suspect this is a meta-analysis of studies, of which some may or may not have been high enough quality to define their terms, and probably several of which used "lifetime" to mean some estimated property of a distribution, and this meta-analysis completely failed to figure out what the included studies were talking about.
So I rate this meta-analysis as almost entirely useless, on account of it failing to actually analyze anything that makes sense.
So I don't think any conclusions can be drawn. Although... ACS puts the lifetime risk of colorectal cancer at 1:25 or so. So one might naively translate a 110-day lifetime extension for everyone to a 110 day · 25 = 2750 day = ~7.5 year expected lifetime extension for people who actually get colorectal cancer. Sign me up -- 7.5 more expected years of life and presumably more than that of quality life years in the event I contract a not-particularly-rare disease sounds like a pretty good deal. (Colorectal cancer screening is not all that unpleasant, and I apparently only have a 96% chance of the screening being unnecessary.)
https://jamanetwork.com/journals/jamainternalmedicine/fullar...
and I do not like it. It suffers from what I consider an extremely common problem in statistics: if you define the question poorly, then your output is garbage no matter how fancy or careful your analysis is.
We can start with the beginning of the abstract:
> Importance Cancer screening tests are promoted to save life by increasing longevity, but it is unknown whether people will live longer with commonly used cancer screening tests.
I have never heard of a doctor suggesting a cancer screening by saying "this might save your life by increasing your longevity." What does that even mean?
So let's try to figure it out. The paper uses the terms "lifetime" and "longevity" somewhat interchangeably, and it does not define either term. The best I can figure out is that, for an individual deceased person, they have a certain lifetime in days from when they were screened to when they because deceased. (Or a certain lifetime in days from birth to death, and I'm not sure this distinction matters.)
Great, but this is only for one patient. What about for a sample of patients or for a population in general or for the probability distribution of lifetimes of a given patient conditioned on whether they do or do not get screened? The article does not say, and a single "lifetime" number is not a probability distribution. Is it an expected value or a mean? A median? A mode? No comment.
One of the headline conclusions is:
> Based on the observed relative risks for all-cause mortality and the reported follow-up time in the trials, the only screening test that significantly increased longevity was sigmoidoscopy, by 110 days (95% CI, 0-274 days) (Table 2, Figure 2)
Figure 2 is useless. Table 2 is somewhat informative, and it has a column for relative risk of all-cause mortality and a column for lifetime gained and its 95% CI. But WAIT A MOMENT! The only way you can know the lifetime of an individual patient is if they're dead. If they're dead, their risk of all-cause mortality by the time they died is 100%. That's not 100% plus or minus something with some relative risk thrown in -- they are dead enough to have a date of death so that someone could compute their lifetime! Or maybe "lifetime" means something else, and the authors didn't bother to figure it out and say what they meant. So what exactly is this paper even analyzing?
So I suspect this is a meta-analysis of studies, of which some may or may not have been high enough quality to define their terms, and probably several of which used "lifetime" to mean some estimated property of a distribution, and this meta-analysis completely failed to figure out what the included studies were talking about.
So I rate this meta-analysis as almost entirely useless, on account of it failing to actually analyze anything that makes sense.
So I don't think any conclusions can be drawn. Although... ACS puts the lifetime risk of colorectal cancer at 1:25 or so. So one might naively translate a 110-day lifetime extension for everyone to a 110 day · 25 = 2750 day = ~7.5 year expected lifetime extension for people who actually get colorectal cancer. Sign me up -- 7.5 more expected years of life and presumably more than that of quality life years in the event I contract a not-particularly-rare disease sounds like a pretty good deal. (Colorectal cancer screening is not all that unpleasant, and I apparently only have a 96% chance of the screening being unnecessary.)
> Colorectal cancer screening is not all that unpleasant
Also not that harmless as you think. Only you suggest to perform it on 24 other patients who won't ever have a colon cancer. And that might be you, right? With the real risk (albeit small, but you need to multiply it by 25) of having a serious complication which eventually may result in a premature death.
Also not that harmless as you think. Only you suggest to perform it on 24 other patients who won't ever have a colon cancer. And that might be you, right? With the real risk (albeit small, but you need to multiply it by 25) of having a serious complication which eventually may result in a premature death.
> explained that if breast cancer caused 3% of all female deaths and screenings reduced these deaths by 35%, that’s a good result on its own. But screenings may change mortality overall by only about 1%
This statement makes it clear what's going on. In ML terms: class imbalance. 99.9% of people won't ever get colon cancer, and therefore won't ever benefit from a colonoscopy. It won't make any statistical difference in overall population survival. But for the 0.1%? It will save their lives.
This statement makes it clear what's going on. In ML terms: class imbalance. 99.9% of people won't ever get colon cancer, and therefore won't ever benefit from a colonoscopy. It won't make any statistical difference in overall population survival. But for the 0.1%? It will save their lives.
> 99.9% of people won't ever get colon cancer, and therefore won't ever benefit from a colonoscopy.
But they may have complications from a colonoscopy, that's the idea. No test is completely harmless, even a blood work. You save some lives but may loose others, that's the point of the paper. And of course you waste resources that can be used to find a cure.
But they may have complications from a colonoscopy, that's the idea. No test is completely harmless, even a blood work. You save some lives but may loose others, that's the point of the paper. And of course you waste resources that can be used to find a cure.
I understand the comment's thesis, but I'd like to see more accurate numbers used where real health outcomes are concerned.
The lifetime risk of being diagnosed with colorectal cancer is ~4%. (With the odds trending higher for the younger generation.) The risk of _death_ from this cancer is ~1%.
The lifetime risk of being diagnosed with colorectal cancer is ~4%. (With the odds trending higher for the younger generation.) The risk of _death_ from this cancer is ~1%.
Yes, and if you perform dozens of tests per year on the general population, and take action based on the results, then the probabilities add up pretty rapidly.
I am still disturbed by this though. The alternative I see to "get screenings" is "get no screenings." If you're one of the ones who actually do have an aggressive cancer, and you don't find out about it until it's like Stage Four, then you just definitely die, badly and soon. You, specifically, might have been helped if screened when you had a little baby tumor.
So, while I see the "statistically" part, asking everyone to get zero screenings until you start coughing up blood (or whatever happens when the cancer starts showing very obvious signs)... it just seems weird on the individual level. Nobody knows (nor can they know) if you're the person who would be cured with treatment, or if you're the person whose outcome wouldn't have changed a bit with treatment (for better or for worse). That question matters individually, and while "statistically you're slightly more likely to be in the second group" according to these studies, that doesn't make me feel great about just declining all screenings.
So, while I see the "statistically" part, asking everyone to get zero screenings until you start coughing up blood (or whatever happens when the cancer starts showing very obvious signs)... it just seems weird on the individual level. Nobody knows (nor can they know) if you're the person who would be cured with treatment, or if you're the person whose outcome wouldn't have changed a bit with treatment (for better or for worse). That question matters individually, and while "statistically you're slightly more likely to be in the second group" according to these studies, that doesn't make me feel great about just declining all screenings.
> You, specifically, might have been helped if screened when you had a little baby tumor.
Or your screening might have caused that tumor? X-rays are not harmless and they can cause cancer. Other screenings have their respective complications. Aren't you disturbed by a thought that maybe you wouldn't have any cancer if not for screening? Or you would have a healthy colon if not for the intern who perforated it during colonoscopy?
Or your screening might have caused that tumor? X-rays are not harmless and they can cause cancer. Other screenings have their respective complications. Aren't you disturbed by a thought that maybe you wouldn't have any cancer if not for screening? Or you would have a healthy colon if not for the intern who perforated it during colonoscopy?
What surprising to me is that sigmoidoscopy shows a benefit but colonoscopy doesn’t.
In colonoscopy, the entire colon is examined by using a long flexible tube. In sigmoidoscopy, only the lower portion of the colon is checked, again by using a flexible tube.
The things that come to mind is that sigmoidoscopy may be better tolerated by patients or have fewer complications.
In colonoscopy, the entire colon is examined by using a long flexible tube. In sigmoidoscopy, only the lower portion of the colon is checked, again by using a flexible tube.
The things that come to mind is that sigmoidoscopy may be better tolerated by patients or have fewer complications.
Likely that the cancers found by the sigmoid are the ones that reduce life years. Perhaps the cancers that are found and treated higher up the colon would have been found out in other ways or not serious enough? I'm not a doctor, so not sure.
Indeed there are dramatic differences between ascending and descending colon cancers.
They are also dissimilar in their chances of presenting early with symptoms making screening less useful vs those that don't present early.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6089587/
They are also dissimilar in their chances of presenting early with symptoms making screening less useful vs those that don't present early.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6089587/
This article uses extremely contorted logic. Pretty much all health care has some cost, and hopefully some benefit in terms of life expectancy and/or quality-of-life-adjusted life expectancy.
If you assume all the costs are fungible, then the analysis is straightforward (the costs are not actually fungible -- some things cost money, other things cost patient time, or use resources that are in finite supply -- so it turns into a linear programming problem, and we've been able to solve those since before computers existed).
With fungible costs, for each of the available health care services, you the expected increase of life expectancy and divide it by the cost, and prioritize the things that have the highest benefit/cost ratio.
The article doesn't talk at all about the cost of the screens, which is fairly low (vs. spending time exercising, or a year of exotic chemo). It also doesn't look at patient quality of life.
If you assume all the costs are fungible, then the analysis is straightforward (the costs are not actually fungible -- some things cost money, other things cost patient time, or use resources that are in finite supply -- so it turns into a linear programming problem, and we've been able to solve those since before computers existed).
With fungible costs, for each of the available health care services, you the expected increase of life expectancy and divide it by the cost, and prioritize the things that have the highest benefit/cost ratio.
The article doesn't talk at all about the cost of the screens, which is fairly low (vs. spending time exercising, or a year of exotic chemo). It also doesn't look at patient quality of life.
Wow. People really are bad at reasoning about probabilities. A more important question might be "does not getting cancer treatments lead to a shortened lifespan?" And that is exactly the question they did not ask in that study.
> In this systematic review and meta-analysis of 18 long-term randomized clinical trials involving 2.1 million individuals, colorectal cancer screening with sigmoidoscopy prolonged lifetime by 110 days, while fecal testing and mammography screening did not prolong life…
That is shockingly bad. An extra three months of life is not nothing, but not exactly a clear win to push people towards the added stress and effort to be screened.
That is shockingly bad. An extra three months of life is not nothing, but not exactly a clear win to push people towards the added stress and effort to be screened.
What about quality of life? Colon cancer did not kill my wife's Grandma, but complications of the surgery did.
The patient is not interested in the effect on the average life expectancy of all people in society, they are only interested in their own case when they are diagnosed early enough to have treatment that will extend their life if they have cancer. This is a different sub-population.
That's not the criteria for population level interventions. This is to answer the question of whether should the USPSTF make a positive recommendation and force insurers to pay or if public health systems should adopt this.
You're conflating this with individual patient decisions.
You're conflating this with individual patient decisions.
Recent and related:
The real cost of a preventive health scan goes well beyond the price tag - https://news.ycombinator.com/item?id=37266189 - Aug 2023 (254 comments)
The real cost of a preventive health scan goes well beyond the price tag - https://news.ycombinator.com/item?id=37266189 - Aug 2023 (254 comments)
My wife's grandpa was diagnosed with prostate cancer. He was 82 and had been a natural food store owner for over 30 years. He said the side effects to the treatment and the surgery was too great for him to endure and would impede his quality of life. He passed away 4 years later from pneumonia unrelated to the cancer. The cancer wasn't easy to deal with in those four years. He wasn't cut up and on chemo or radiation either. I agree with him in that too much can be "done"
There is a really weird connotation with this: if when malignancy is found and then actions are taken and when it's found earlier actions are taken earlier but they still don't survive means that when you treat a cancer early is the same as treating it late. But that is contrary to all studies ever done. So either there is some mistake or stage I with stage 3 cancer have the same survival. Look like someone fucked up some math imo.
It could also mean there are other negative forces balancing out the positive forces. Negative outcomes for broad screening include.
- Early testing means more visits to the hospitals/clinics. Those are famously dangerous places to get sick.
- False positives mean unneeded treatment. That can shorten your life.
- Finding things earlier also means earlier treatment. That can kill you. Every trip to a hospital means a non-zero risk of catching MRSA and other nasties.
- Some things would be handled by the immune system anyway. The treatment might provide no benefit over an ignorant outcome.
I also find it easy to believe that among all the oncologists and hospitals, some of them might be at best neutral, or even net-negative in mortality and morbidity. This is about the whole population, not just leading units at famous hospitals. There are doctors out there with the ethics of a bent mechanic.
- Early testing means more visits to the hospitals/clinics. Those are famously dangerous places to get sick.
- False positives mean unneeded treatment. That can shorten your life.
- Finding things earlier also means earlier treatment. That can kill you. Every trip to a hospital means a non-zero risk of catching MRSA and other nasties.
- Some things would be handled by the immune system anyway. The treatment might provide no benefit over an ignorant outcome.
I also find it easy to believe that among all the oncologists and hospitals, some of them might be at best neutral, or even net-negative in mortality and morbidity. This is about the whole population, not just leading units at famous hospitals. There are doctors out there with the ethics of a bent mechanic.
> But experts say this doesn’t mean you should cancel that colonoscopy or mammogram appointment.
That can only be that these experts disagree with the study, because if it were properly conducted such that its findings are true, then in fact its conclusions do add up to skipping colonoscopies and mammograms.
The study is saying that the diagnostic procedures have no effect on outcome. You should not waste time on procedures that don't change outcome.
That can only be that these experts disagree with the study, because if it were properly conducted such that its findings are true, then in fact its conclusions do add up to skipping colonoscopies and mammograms.
The study is saying that the diagnostic procedures have no effect on outcome. You should not waste time on procedures that don't change outcome.
The article dismisses a population-wide life expectancy increase of 4 months from one of the screens.
If that's your bar, then most preventative screening is probably not worthwhile.
If that's your bar, then most preventative screening is probably not worthwhile.
If, say, only 5% of the people undertake that screening and manage to bring up the population expectancy by four months, then the actual effect could be over six years for screened individuals.
It's pretty dishonest to be confusing the effect of screening by counting unscreened individuals.
It's like claiming that seat belts don't work by looking only at fatality figures that don't inform to what extent seatbelts were worn.
It's pretty dishonest to be confusing the effect of screening by counting unscreened individuals.
It's like claiming that seat belts don't work by looking only at fatality figures that don't inform to what extent seatbelts were worn.
It would really help me to use the same methodology but compare it to people smoking like they did in the 1980s.
Is this study just proving that other things kill you while you're being or after you've been treated for cancer?
It provides evidence that a diagnostic approach to healthcare misunderstands that good health is a complex expression of a million factors, and not a function of the number of healthcare interventions.
A diagnostic approach to healthcare can be easily bureaucratized (come collect your stamp after your colonoscopy!). A touchy-feely "million factors" approach cannot.
A diagnostic approach to healthcare can be easily bureaucratized (come collect your stamp after your colonoscopy!). A touchy-feely "million factors" approach cannot.
Someone else linked to https://thennt.com/nnt/screening-mammography-for-reducing-de...
Quote:
> "Two recent data reviews deserve further mention. The United Kingdom commissioned an independent review after dissenting voices swelled, for the purpose of better informing shared decision making and educational materials about the harms and benefits of screening.6 Unfortunately the review concluded that screening mammography trials were inadequately powered to detect an impact on all-cause mortality, and therefore used breast cancer mortality as a primary outcome. They concluded a 20% reduction and used this in their discussion of harms and benefits. As noted above, cause-specific mortality is both scientifically unstable (conclusion reversal is common when all-cause mortality is considered)7 and disease-centered rather than patient centered (patients would prefer to avoid death altogether). Thus, either screening mammography does not save lives or else we have inadequate data to say whether it does or does not. In neither case can a benefit be scientifically claimed."
> "They concluded a 20% reduction and used this in their discussion of harms and benefits."
We want to do things that will help people. On an individual level, people have the right to make decisions for themselves. At the population level, we should do things that can be proven to be helpful. This leads to decisions that feel heartless - denying people a vaccine during a deadly pandemic while it is being tested; delaying or denying introduction of a new medicine that shows only marginal improvements over an old one.
So their independent review showed benefit by changing the criteria for comparison. We want to help people, and medical interventions feel like helping. Unfortunately, sometimes they can be the equivalent of The Politician's Fallacy: "There was a problem. I did something about the problem. Therefore the problem is fixed"
> "As noted above, cause-specific mortality is both scientifically unstable (conclusion reversal is common when all-cause mortality is considered)7 and disease-centered rather than patient centered (patients would prefer to avoid death altogether)."
People die of /something/. That thing becomes a target to fix; and we deploy resources to fix it. We become emotionally connected to some interventions. (Speaking personally, I'm participating in a bike ride in a few weeks to raise money for breast cancer screenings.) Some of those resources are beneficial, some are not, some may be harmful.
> "Thus, either screening mammography does not save lives or else we have inadequate data to say whether it does or does not. In neither case can a benefit be scientifically claimed."
Quote:
> "Two recent data reviews deserve further mention. The United Kingdom commissioned an independent review after dissenting voices swelled, for the purpose of better informing shared decision making and educational materials about the harms and benefits of screening.6 Unfortunately the review concluded that screening mammography trials were inadequately powered to detect an impact on all-cause mortality, and therefore used breast cancer mortality as a primary outcome. They concluded a 20% reduction and used this in their discussion of harms and benefits. As noted above, cause-specific mortality is both scientifically unstable (conclusion reversal is common when all-cause mortality is considered)7 and disease-centered rather than patient centered (patients would prefer to avoid death altogether). Thus, either screening mammography does not save lives or else we have inadequate data to say whether it does or does not. In neither case can a benefit be scientifically claimed."
> "They concluded a 20% reduction and used this in their discussion of harms and benefits."
We want to do things that will help people. On an individual level, people have the right to make decisions for themselves. At the population level, we should do things that can be proven to be helpful. This leads to decisions that feel heartless - denying people a vaccine during a deadly pandemic while it is being tested; delaying or denying introduction of a new medicine that shows only marginal improvements over an old one.
So their independent review showed benefit by changing the criteria for comparison. We want to help people, and medical interventions feel like helping. Unfortunately, sometimes they can be the equivalent of The Politician's Fallacy: "There was a problem. I did something about the problem. Therefore the problem is fixed"
> "As noted above, cause-specific mortality is both scientifically unstable (conclusion reversal is common when all-cause mortality is considered)7 and disease-centered rather than patient centered (patients would prefer to avoid death altogether)."
People die of /something/. That thing becomes a target to fix; and we deploy resources to fix it. We become emotionally connected to some interventions. (Speaking personally, I'm participating in a bike ride in a few weeks to raise money for breast cancer screenings.) Some of those resources are beneficial, some are not, some may be harmful.
> "Thus, either screening mammography does not save lives or else we have inadequate data to say whether it does or does not. In neither case can a benefit be scientifically claimed."
so this is almost like a Goodhart's Law problem
I think it is a tricky measurement problem for sure. In this case, it feels like there is an obvious measurement (individual outcomes) that you have to deliberately step around to see the better measurement. That deliberate decision to ignore individual success stories feels very callous.
This is not an unexpected result. Last I checked breast self examination also does not reduce deaths from breast cancer, nor testicular self examination.
If anyone's interested the "Wilson criteria" is the basis of decisions about screening programmes and many run programmes fail it.
If anyone's interested the "Wilson criteria" is the basis of decisions about screening programmes and many run programmes fail it.
Sounds like a talking point one would use if you no longer wanted to provide coverage for preventive care.
discussed here - https://news.ycombinator.com/item?id=37296122
I found this comment useful: - https://news.ycombinator.com/item?id=37297963
Several comments noted that a 4 month improvement in life expectancy (for sigmoidoscopy) over the whole population is actually pretty good for a low-incidence cancer. That's several years for the people who actually get it.
But the comments seem naive about the downsides of broad screening: over-treatment, iatrogenic disease, false positives, opportunity cost, etc.
I found this comment useful: - https://news.ycombinator.com/item?id=37297963
Several comments noted that a 4 month improvement in life expectancy (for sigmoidoscopy) over the whole population is actually pretty good for a low-incidence cancer. That's several years for the people who actually get it.
But the comments seem naive about the downsides of broad screening: over-treatment, iatrogenic disease, false positives, opportunity cost, etc.
(this comment was originally posted to https://news.ycombinator.com/item?id=37312540, but we've merged that thread hither. that's why the comment links to its own thread now)
Does that mean early cancer treatments don't prolong life?
Positive screening result usually leads to treatment of one kind or another. Without screening, treatment would start later, if at all. Is that a corollary of this study?
Positive screening result usually leads to treatment of one kind or another. Without screening, treatment would start later, if at all. Is that a corollary of this study?
What's the next question then? Curious to know if any of these screening caught cancers at various stages and if there is a correlation to better long term prognosis.
These articles are dangerous for the public. They may not go to have their regular checkups that will make them die younger and thus ironically yeah their life would not be extended any more.
Still it's nice to be the one outlier. For those with higher risk it would still be a good idea. Smokers, people who work with chemicals etc.
[deleted]
Breast cancer screens def save lives. Can't speak to all screenings but some def work.
Except breast cancer screening, at least via mammography, doesn't save lives. See, for example: https://thennt.com/nnt/screening-mammography-for-reducing-de...
I worked in a lab doing cancer detection via image AI (mammograms, mri, etc) back in 2008 or so, and even then we knew that mammography didn't save lives.
Read all of the caveats. None of this is still relevant. Cancer-specific mortality is definitely reduced.
There is no study powered enough to draw conclusions on all-cause mortality, which may not be the best measure anyway.
There is no study powered enough to draw conclusions on all-cause mortality, which may not be the best measure anyway.
oh wow.
"This is an important, though uncommonly discussed, issue in the translation of evidence from cancer screening trials.1 It is known that overdiagnosis (treatment of cancers that would have been no threat), and high false positive rates (misdiagnosis) lead to medical harms and unnecessary surgeries, chemotherapy, and radiation...
...margin of benefit suggested by the analysis above it seems likely that if there is a benefit to screening mammography it is balanced out by mortal harms from overdiagnosis and false-positives"
"This is an important, though uncommonly discussed, issue in the translation of evidence from cancer screening trials.1 It is known that overdiagnosis (treatment of cancers that would have been no threat), and high false positive rates (misdiagnosis) lead to medical harms and unnecessary surgeries, chemotherapy, and radiation...
...margin of benefit suggested by the analysis above it seems likely that if there is a benefit to screening mammography it is balanced out by mortal harms from overdiagnosis and false-positives"
[deleted]
Cancer treatment isn't a complete positive. If you subject large numbers of people to it some of them will die from the treatment. If you save 1 person from cancer but kill 5 more that didn't have it, is that a net positive?
"mammography screening did not prolong life" from the abstract.
If you are unfortunately talking about a personal experience, sorry, but you can't confuse n=1 stories with large research studies.
If you are unfortunately talking about a personal experience, sorry, but you can't confuse n=1 stories with large research studies.
I don't know why you're downvoted. The commenters below are misunderstanding things, the NNT page is old and even then it's being mis-cited. I won't go into it but read the caveats section for the author's own explanation.
Screening mammography unequivocally improves cancer-specific mortality. Making the leap to overall mortality is hard, and even a meta analysis is likely too underpowered given the very low overall mortality to begin with. Recall that the smaller the absolute difference is the larger the study will have to be to detect the difference.
For breast cancer we would probably be talking about something like 10 million patients to be adequately powered to draw any conclusion. The older trials also aren't useful/can't be used because the diagnosis and treatment of breast cancer is dramatically different than it was 10 years ago when BI-RADS was in its nascent stage. Accordingly it's not even possible to conduct such a study as it would be unethical to randomize millions of patients to no screening when we know it has proven benefits.
This also raises the question of which outcome measure matters more? All-cause mortality is a good one but it has both pros and cons. Pros being it captures hidden and misattributed deaths and is the least susceptible to bias. Cons include that it underestimates the impact of diseases that aren't high causes of death (i.e. if the patient population is more likely to die of something else the all-cause mortality won't change).
All of this leads to what are we trying to solve with breast cancer screening? It's unequivocal that a screen detected breast cancer is less advanced (i.e. no systemic therapy required) and is associated with cancer-related mortality benefit. The harms of overdiagnosis have also significantly lessened with modern radiology/histology classifications, biopsy techniques and treatment algorithms. Is cancer-specific mortality good enough? I would argue yes given the significant morbidity with systemic therapy and metastatic disease.
To summarize:
1. Screening mammography has been proven to reduce cancer specific mortality in many studies.
2. The only accurate statement about all-cause mortality is "we don't know" rather than yes/no. None of the studies are powered or controlled enough to draw any conclusions.
3. All-cause mortality may not be the best outcome measure to determine whether an intervention is "saving lives" and certainly is not the only measure to consider when deciding on a screening program.
Screening mammography unequivocally improves cancer-specific mortality. Making the leap to overall mortality is hard, and even a meta analysis is likely too underpowered given the very low overall mortality to begin with. Recall that the smaller the absolute difference is the larger the study will have to be to detect the difference.
For breast cancer we would probably be talking about something like 10 million patients to be adequately powered to draw any conclusion. The older trials also aren't useful/can't be used because the diagnosis and treatment of breast cancer is dramatically different than it was 10 years ago when BI-RADS was in its nascent stage. Accordingly it's not even possible to conduct such a study as it would be unethical to randomize millions of patients to no screening when we know it has proven benefits.
This also raises the question of which outcome measure matters more? All-cause mortality is a good one but it has both pros and cons. Pros being it captures hidden and misattributed deaths and is the least susceptible to bias. Cons include that it underestimates the impact of diseases that aren't high causes of death (i.e. if the patient population is more likely to die of something else the all-cause mortality won't change).
All of this leads to what are we trying to solve with breast cancer screening? It's unequivocal that a screen detected breast cancer is less advanced (i.e. no systemic therapy required) and is associated with cancer-related mortality benefit. The harms of overdiagnosis have also significantly lessened with modern radiology/histology classifications, biopsy techniques and treatment algorithms. Is cancer-specific mortality good enough? I would argue yes given the significant morbidity with systemic therapy and metastatic disease.
To summarize:
1. Screening mammography has been proven to reduce cancer specific mortality in many studies.
2. The only accurate statement about all-cause mortality is "we don't know" rather than yes/no. None of the studies are powered or controlled enough to draw any conclusions.
3. All-cause mortality may not be the best outcome measure to determine whether an intervention is "saving lives" and certainly is not the only measure to consider when deciding on a screening program.
> 1. Screening mammography has been proven to reduce cancer specific mortality in many studies.
So let's assume that an annual X-ray caused another cancer in women who would never develop breast cancer (i.e. 87% of them). You are saying "we don't know", but the authors of that paper are trying to answer exactly that. We may have saved lives in 13% group (that would be < 2.5% of those dying from breast cancer), but may have lost some lives in 87% group. According to the paper the net outcome is around 0.
So let's assume that an annual X-ray caused another cancer in women who would never develop breast cancer (i.e. 87% of them). You are saying "we don't know", but the authors of that paper are trying to answer exactly that. We may have saved lives in 13% group (that would be < 2.5% of those dying from breast cancer), but may have lost some lives in 87% group. According to the paper the net outcome is around 0.
Evidence?
It's unequivocal that screening reduces breast-cancer specific mortality. None of the studies are powered enough to draw a positive or negative conclusion for overall mortality. The second last link is an explanation of why this is the case, where we're at and what the implications are.
The last link explains the NCCN rationale and decision making process.
http://www.aapec.org/images/b69a380d-519a-415b-8e8c-8e7f2b02...
https://www.nejm.org/doi/full/10.1056/nejmoa1000727
https://academic.oup.com/jnci/article/106/11/dju261/1496367?...
https://www.bmj.com/content/bmj/352/bmj.h6080.full.pdf
https://jnccn.org/view/journals/jnccn/16/11/article-p1398.xm...
The last link explains the NCCN rationale and decision making process.
http://www.aapec.org/images/b69a380d-519a-415b-8e8c-8e7f2b02...
https://www.nejm.org/doi/full/10.1056/nejmoa1000727
https://academic.oup.com/jnci/article/106/11/dju261/1496367?...
https://www.bmj.com/content/bmj/352/bmj.h6080.full.pdf
https://jnccn.org/view/journals/jnccn/16/11/article-p1398.xm...
[deleted]
Me before reading: "this study, like ~every study, will detect no effect on all-cause mortality because that needs a crazy big sample size"
After reading: "this study, like ~every study, detected no effect on all-cause mortality because that needs a crazy big sample size"
A three-year study where one group magically had zero car crashes would need a sample size of 5,000,000 to detect a difference in all-cause mortality. It's really hard. (80% chance of p < 0.05)
After reading: "this study, like ~every study, detected no effect on all-cause mortality because that needs a crazy big sample size"
A three-year study where one group magically had zero car crashes would need a sample size of 5,000,000 to detect a difference in all-cause mortality. It's really hard. (80% chance of p < 0.05)
They actually did show an improvement of all-cause mortality for one of the screens (corresponding to a 4 month increase in life expectancy), and "insignificant" improvements in others.
(The headline is probably technically true, but I think it is intentionally misleading and disingenuous.)
(The headline is probably technically true, but I think it is intentionally misleading and disingenuous.)
[deleted]
> “Cancer screening was never really designed to increase longevity. Screenings are really designed to decrease premature deaths from cancer.” Explained another way, Dahut said, if a person’s life expectancy at birth was 80, a cancer screening may prevent their premature death at 65, but it wouldn’t necessarily mean they’d live to be 90 instead of the predicted 80.
Personally I think this is just a matter of terminology in public health not necessarily aligning with our intuitive understanding. I presume most people would think that preventing a shortening of lifespan is prolonging your life, but the article makes clear that they are different.