Colorectal cancer starts in the colon or rectum, both of which are parts of the large intestine. Most colorectal cancers are adenocarcinomas, or cancers that begin in cells that make and release mucus and other fluids. Colorectal cancer often begins as a growth called a polyp, which may form on the inner wall of the colon or rectum. Some polyps develop into cancer, so detecting and removing the polyps is imperative to preventing colorectal cancer altogether.

It is recommended that colorectal cancer screening begin at age 45 and continue until age 75. The decision to screen for colorectal cancer in adults aged 76 to 85 years should be an individual one made with the provider, considering the patient’s overall health and prior screening history.