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Most cancer screenings don’t extend life, study finds

cnn.com

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Re: Most cancer screenings don’t extend life, study finds

#11

Post by orblivion »

kccqzy wrote: post #3

This is the pertinent quote: > “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…

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.

Re: Most cancer screenings don’t extend life, study finds

#12

Post by kiba »

monero-xmr wrote: post #7

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 e…

Exercise also reduces cancer risk.

Re: Most cancer screenings don’t extend life, study finds

#13

Post by somenameforme »

kccqzy wrote: post #3

This is the pertinent quote: > “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…

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...

Re: Most cancer screenings don’t extend life, study finds

#14

Post by kazinator »

> 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.

Re: Most cancer screenings don’t extend life, study finds

#15

Post by kazinator »

kccqzy wrote: post #3

This is the pertinent quote: > “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…

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.

Re: Most cancer screenings don’t extend life, study finds

#16

Post by Retric »

monero-xmr wrote: post #7

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 e…

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?

Re: Most cancer screenings don’t extend life, study finds

#17

Post by circlefavshape »

twoodfin wrote: post #10

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 d…

> 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

Re: Most cancer screenings don’t extend life, study finds

#18

Post by throwway120385 »

amanaplanacanal wrote: post #8
Clent wrote: post #6

Earlier quoted context omitted.

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.

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.

Re: Most cancer screenings don’t extend life, study finds

#20

Post by aydyn »

> 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.

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