My understanding is that it's net negative to test too much.
A lot of men die with prostate cancer, because only very few die from it. And if you belong to the former group, knowing about it or doing any kind of intervention means a massive loss in quality of life. So the best course of action overall is to close our eyes and stop looking. And hope you don't belong to the latter group.
It's an indication that something's wrong with the system. We'd get better overall health outcomes if we tested everyone and told a large cohort of people "you do have cancer, and there are these possible treatments for it, but we recommend you don't take any of those treatments and just hope for the best". But between doctors and patients and other healthcare participants, we collectively can't do this - a large minority of people will freak out and demand treatment and the healthcare providers will feel compelled to go along with it.
Perhaps this plan just needs better marketing. Instead of dividing tumors into benign and malignant we could have a third category for malignant but slow-growing.
MRI machines need to be a) democratized so they're cheaper and everywhere and b) connected to trustworthy clinically-proven radiological AI to identify and watch growths. There's absolutely no rational reason any patients should end up with surprise terminal cancers or surprise coronary artery disease.
(Yes, yes whole body scans exist but these are largely pseudo-medical scams that don't deliver what they promise. I'm saying deliver on it, within reason.)
edit: Ah ok. Risk of over-treatment by broad scanning?
"Active surveillance aims to avoid unnecessary treatment of harmless cancers while still providing timely treatment for those who need it." according to NHS.
No, you don't recover. Many men will get prostate cancer when they're old, but they'll most likely die from something else before that one becomes an issue.
But if we do scan and test and screen, a lot of men will find out they have it, become anxious about it and will want to do something about it, which leads to a lot of unnecessary treatments that decreases people's quality of life and wouldn't extend their lifespan anyway.
A lot of men die with prostate cancer, because only very few die from it. And if you belong to the former group, knowing about it or doing any kind of intervention means a massive loss in quality of life. So the best course of action overall is to close our eyes and stop looking. And hope you don't belong to the latter group.