[canes123456]

It’s more complex than this. There is a pretty narrow sweet spot where early detection actually helps.

If the cancer is very fast growing, it could be too fast for treatment to help at all. Even if treatment helps there likely not a very long period of time before you develop symptoms that would have lead to treatment regardless.

If it is very slow growing, you might outlive the cancer and it doesn’t require treatment. It is effectively but not actually a benign tumor.

You also have to deal with false negative and positives, that could be an order of magnitude higher than the Goldilocks true postives that earlier detection actually made a difference. It’s easy to see how population results will not show much of a benefit.

[jajko]

Probably the most famous slow growing tumor is prostate cancer. As per my friend who is urology surgeon, basically all men eventually catch it, unless they die young. But it goes so slowly and symptoms are rather mild in most cases no invasive treatment is done.