I recommend getting a colonoscopy if you have any symptoms. There is a lot of stigma that prevents people from being proactive about this type of issue.

My anecdote (M, 35) is that I got one after experiencing symptoms that turned out to be unrelated, but they did find pre-cancerous polyps so now I will be getting them more regularly. I received received meaningful early detection and peace of mind. Also aside from the prep, its a very convenient procedure. You get put under anesthesia and do a quick time travel.