An unprecedented window into how diseases take hold years before symptoms appear

This is a well known phenomenon in medicine. It is always carefully considered when making public health decisions regarding e.g. screening programs and intervention best practices.

For example, a PSA test is useful to detect cancer of the prostate, if a male patient has urination problems. But doing general screening for high PSA values in middle aged men is not considered a good idea, because there are too many false positives and it would likely lead to many unnecessary invasive interventions.

It's also why "early detection leads to longer survival" claims in cancer patients has to be treated with quite some care.

Two people develop a fatal cancer at T0. One is diagnosed at T1, the other at T2, both die at T3.

It looks like the first person survived longer with cancer than the second, but they didn't: the interventions had no effect, it's just a statistical artifact.

This is by no means always the case - earlier detected cancer is more treatable - but it still needs to be controlled for.

Have a friend working as urology surgeon - basically all men get prostate cancer, its just a function of time (unless you die young). Most of them is benign, or cause few issues and are often let alone.

If you would run scans on all males above say 45 there would be endless stream of operations happening, all of which would lower quality of life for everybody, and sometimes shorten their lives a bit or a bit more. Any public healthcare system would be brought to the edge of collapse by just this since surgeries are supremely expensive everywhere, that's not just US invention.

Yo, personal experience. I'll be undergoing a second test soon, as a precaution, but the first showed me at "acceptable risk level but cancer is still present".

My urologist carefully assured me ahead of the test that I "do have cancer, as all men my age do", and clarified the difference between "have" and "might well die of".

for anyone else wondering:

https://cdn.mdedge.com/files/s3fs-public/fedprac/images/fed0...

~0.7% at 49 years, 45.5% at 70 years, looks like a logarithmic growth curve

And of course there’s always a riff on the placebo effect even when the intervention isn’t sugar pills. That is, success gets attributed to the approved intervention, but at the nuts & bolts level it had little or no effect. The body cured itself but the treatment gets the credit.