alt Hacker NewsCatching colorectal cancer at an early stage improves survival rates tremendously. You have to weigh the risk of complications from the colonoscopy (primarily bowel perforation) with the improved outcomes. There's a cost element as well, since colonoscopies (without complications) can be several thousand dollars.
That's the calculations that go into screening guidelines. It's a lot of weighing now much benefit early detection provides vs how much harm testing and false positives do.