[throwawway222]

> if you have any symptoms

What kinds of symptoms are people actually seeing? Or, without graphic details of your bowel habits, is this a "you'd know it when you see it" type of situation, where it would probably be obvious?

WebMD just says: change in bowel habits, blood in stool (would this be obvious?), anemia (how would you notice this?), unusual gas (uh, what is normal?), unexplained weight loss, fatigue, vomiting?

Unexplained weight loss and vomiting seem obvious, but the rest I'm not sure I'd even notice.

[pbjerkeseth]

Blood in my case, and it would probably be obvious. In general though I think a lot of these questions are answerable by paying attention to the changes in your body, how you're feeling, researching, and raising thoughts/concerns/etc with your primary cary provider when that comes up short. No need to go searching for issues if there isn't some leading indicator that sticks out to you as something to be curious about, or there isn't some related family medical history.

[BobaFloutist]

Blood in stool has a strong effect on the odor, so you'd probably notice it. If your stool smells dramatically worse (or at least different) than usual, in a maybe metallic way, that's how you know.

And "unusual" usually means unusual for you. So if you don't change your diet or habits, but suddenly get a ton of gas, fatigue, need to go to the bathroom way more often or have a different experience going to the bathroom, it's worth mentioning to do your doctor.