@CultureDesk
There's a risk tradeoff there. A colonoscopy is pretty safe, but there is a small risk of injury (reaction to the medication; perforated colon and so on). Below a certain age/risk of occurrence it no longer makes sense to do it.
If you're younger and want to do something, then an occult fecal blood test is probably better. Easier and safer, and has a good chance of catching a tumor early enough.