I agree with the occult blood test, easy peasy and very useful. I'm an old lab tech, now quite long ago, but it is still, far as I've read, a well regarded thing to do.
One matter I haven't followed up on is that there is an xray version of colonoscopy, said, when I read about it, now maybe six or more years ago, to be better at seeing the whole colon than routine colonoscopies. That was back when I read the New York Times, likely where I read that. Medicare wouldn't then pay for it, which is prohibitive for a bunch of us.
Since I haven't seen news about that since, I'm not pushing it, just still interested.
Oh, and yes, you get to drink the same glop.