FOBT which you can do painlessly at home for a few dollars is not meaningfully less preventative than an invasive colonoscopy and carries almost no risk. https://www.nejm.org/doi/full/10.1056/NEJMoa2208375
Very true, and this is what caught my father's bowel cancer and saved his life.
That said, for someone with increased risk, nothing compares to a colonoscopy - at it does a better job of catching things early, before you start getting blood in your poo.
But if you are at a standard risk, doing a fobt every couple-few years is hugely important. Ask your doctor now!
The superior stool based test would be the FIT-DNA test, which compares favorably to a colonoscopy in sensitivity. These are covered by insurance in the US.
www.nejm.org/doi/full/10.1056/NEJMoa1311194
However, if pre-cancerous polyps are found during a colonoscopy, they can be removed right then.
Of course, the best prevention is one that people actually do.
How effective is it when you get one every year? The idea of a colonoscopy scares the shit out of me (pun not intended).
I have done mine at 50, you are half asleep, does not hurt, you do not remember anything. Fasting day before is the worst part.
All in all, nothing to worry about, just do it.
While earlier detection has been beneficial, there's such a thing as too much. Really, there's balance to be struck. For instance the detection procedures themselves (even things like non-invasive imaging) aren't risk free themselves, false positives can set off a chain of events that carry their own harm, and even it's not at all uncommon to develop cancers you "die with" instead of "die from" but once they're detected you have to assume the worst - and treatment itself causes its own form of harm.
Getting one annually is not recommended for most patients. After my bowel resection, I had annual colonoscopies for five years, then every three years, now every five (the normal recommendation for my age cohort).
Colonoscopies are no big deal from my perspective, but they do have some risk; bowel perforation being the primary one. The prep stuff is the worst aspect for most patients; I used to love lemon lime Gatorade before I used it once as a way of drinking the liquid laxative...
FOBT = Fecal Occult Blood Test (A highly sensitive test for detecting blood in poop even at tiny concentrations).