Next time you see your doctor tell him you read that colonscopies should only be used for cancer surveillance and diagnosis in UC and that your cancer risk isn't elevated until you have had the disease for 8+ years. See what he says. You can print this out and take it with you:
"According to the U.S. Preventive Services Task Force guidelines for colon cancer screening, people who have had IBD throughout the colon for at least 8 years and those who have had IBD in only the left side of the colon for 12 to 15 years should have a colonoscopy with biopsies every 1 to 2 years to check for dysplasia. Such screening has not been proven to reduce the risk of colon cancer, but it may help identify cancer early and improve prognosis. These guidelines were produced by an independent expert panel and endorsed by numerous organizations, including the American Cancer Society, the American College of Gastroenterology, the American Society of Colon and Rectal Surgeons, and the Crohn’s & Colitis Foundation of America."
digestive.niddk.nih.gov/ddiseases/pubs/colitis/#cancer