Familial adenomatous polyposis (FAP) is an inherited condition in which numerous polyps (growths that protrude from mucous membranes) form on the inside walls of the colon and rectum. Having FAP makes it very likely that a person will get colorectal cancer.

People with FAP develop polyps in their 20s and 30s or even earlier. They may have hundreds to thousands of polyps throughout the colon by their 30s. Surgery to remove the colon (colectomy) is the recommended treatment, because FAP almost always develops into colon cancer.

The gene mutation that causes FAP can be detected by a genetic screening blood test. If the test result is positive, immediate family members should also be screened. Yearly screening with sigmoidoscopy beginning at age 10 or 12 is recommended. After polyps are found, surgery to remove the colon (colectomy) should be done to prevent colon cancer.