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Comment by doctoboggan | Hacker News Reader

Do they somehow control for changing (improving) detection capabilities? I did see this mentioned:

> Additionally, the increased use of diagnostic testing and overdiagnosis probably contributed to the rise in incidence rates of cancers that are highly sensitive to diagnostic scrutiny

So they did consider it, but I am not sure if/how they attempted to control for it.

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There was another link that passed through HN recently regarding cancer rates increasing over time. I don't have time at the moment to dig it up and give this topic a proper treatment, but one thing I remember from that discussion was that while incidence rates have increased (which is almost certainly influenced by detection), over the last few decades we see cancer mortality rate, at least in the developed world, being flat to down.

These random graphs from the study kind of support that, https://www.thelancet.com/cms/attachment/7e57a199-90a6-4451-... , again don't really have time to dig it all up at the moment but I think the previously linked study on HN had graphs for cancer mortality in various Western countries - again most of them trending slightly down.

So I mean, try to live healthy, keep your fingers crossed, knowing that the treatments are getting better all the time. Beyond that, if you're not an oncologist, how much should you really worry about this stuff.

Careful most mortality rates are at 5 years. The fact that some patients are maintained alive longer doesn't say anything about their living condition and the final outcome.

All the cancers were diagnosed between 2000-2019 and they didn't check the incidence by year but by birth date of victims. So the testing should not affect, unless diagnostic procedures are 2 times more effective in young people.

no, they just mentioned it because they're aware of that but cannot control it and might affect the end result. makes sense - it used to be underdiagnosed and now with bigger push for prevention this might introduce more false positives.

It's sufficiently important for interpreting their results that it should be in the abstract

Too bad glioblastoma and pancreatic cancer remain stubbornly resistant to long-term remission.

Or even short-term for that matter: even for localized pancreatic adenocarcinoma (not metastasized to lymph nodes or beyond) only 50% of patients survive their first year. For glioblastoma it is even worse: only 25% one-year survival rate

There are some promising developments for glioblastoma actually!

explain

CART therapies and mRNA vaccines are having breakthrough level results in recent studies.

It’s an amazing time in that space. My poor late wife succumbed to metastatic melanoma last year. In 2010, the chances of living a year was 0. Now 5 year survival rates are 65% thanks to immunotherapy. Unfortunately, complications delayed treatment for my wife and she was one of the 35%.

In the next decade, many brain cancers will be curable. Unfortunately, those breakthroughs are built on the shoulders of those who come before us.

They discuss trying to separate period effects (which would include improvements in detection) from cohort effects. Here's what they say about it:

> To evaluate birth cohort trends in cancer rates, adjusted for age and period effects, we fitted age-period-cohort models to the incidence or mortality rates of each cancer type using weighted least squares, assuming Poisson-distributed counts and including overdispersion parameters for potential extra-Poisson variation. A change in the birth cohort trend usually indicates changes in exposure prevalence, leading to varying risks of developing cancers for individuals of the same generation. By contrast, a period effect reflects systematic changes in cancer ascertainment or the influence of newly introduced or improved medical interventions, affecting all age groups simultaneously during the same period.

I was somewhat surprised that cohort effects are tied to changes in exposure prevalence, when I would have assumed those would give rise to period effects. Presumably exposure during childhood carries lifelong consequences.

Also, you're excluding people who have died of several other causes in the older cohort. Including causes that are perfectly preventable today or others that might have had a correlation

Well, it looks to me like they look at 34 types of cancer, and found that 8 of those were increasing.

So "we detect cancer better" isn't really a good theory, unless it just so happens we only have improved our detection for 8 of those cancers.

Would love for somebody more knowledgeable who read the whole paper to weigh-in.

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