[gwd]

> People will read this headline and conclude that they don’t need to get a colonoscopy which I don’t think follows from this study at all.

What this appears to show is that you need to get a colonoscopy to avoid colon cancer; but that you don't need to get a colonoscopy to avoid death. I'd much rather avoid colon cancer entirely than have colon cancer and survive.

But as GP pointed out, maybe you need something else to avoid death: something that is correlated with responding to the invitation to get a colonoscopy. Maybe if you're willing and able to get a colonoscopy when invited, you're willing and able to more pro-actively go to the doctor when you notice other issues that are indicative of colon cancer, allowing you to get early treatment. And conversely, maybe if you're not willing or able to get a colonoscopy when invited, you're more likely to ignore symptoms until it's too late.

Again, avoiding colon cancer in the first place is better than successfully treating it; but it does point to the fact that other interventions might be more helpful in actually preventing deaths.

[kashunstva]

> And conversely, maybe if you're not willing or able to get a colonoscopy when invited, you're more likely to ignore symptoms until it's too late.

Yes. This is the argument against relying on the secondary analysis in this study. Although the invited and standard care groups were randomized such that differences in putative confounders were adjusted for, the rejection of the intervention itself may have reintroduced systematic differences that reduce the reliability of the hypothesis that intention to screen for colon cancer reduces mortality. Possibly those who accepted screening colonoscopy are more attentive to other health and lifestyle practices that reduce colon cancer mortality.