Die.
Colonoscopy absolutely reduces cancer death, no doubt about it. The test itself isn't magical with genetics. Even the removal of a polyp that prevents it from becoming cancerous is debatable. Colonoscopy is a screening test.
Funny you bring up pap smears. 10 years from now pap testing is going to be very different and will likely be recommended in non-immunized patients. We already see this in patients that can go 3-5 years without a pap if they hpv is negative. Pap is a screening test.
Prevention...HPV vaccine. Cholesterol medications. BP medicines. Those are prevention.
Nomenclature matters.