Average-risk individuals should begin colorectal cancer screening with colonoscopy at what age?

• A. 50
• B. 45
• C. 55
• D. 60

Answer: (A)

Starting at age 50 for average-risk individuals is the standard you’re being tested on. The rationale is that colorectal cancer risk rises with age, so beginning screening at 50 helps catch precancerous polyps when they’re most easily removed and before cancer develops, which reduces mortality. Colonoscopy is favored because it directly visualizes the entire colon and allows removal of polyps during the same procedure, so if the exam is normal, the next screening is usually scheduled about 10 years later. If there are risk factors—such as a family history of colorectal cancer, inflammatory bowel disease, or known hereditary syndromes—screening would typically start earlier. The other ages would either miss polyp development early enough to prevent cancer or start later than is optimal for average risk.