Hereditary genetic defects (inherited polyp syndromes) increase the risk for developing colorectal cancer. Two syndromes that increase the risk for colon polyps and colorectal cancer are familial adenomatous polyposis (FAP) and hereditary nonpolyposis colon cancer (HNPCC).

Familial adenomatous polyposis (FAP)

People who have FAP have a genetic abnormality called the APC gene mutation.

FAP causes the early development of adenomatous polyps. People with this syndrome develop polyps in their 20s and 30s or even earlier, have hundreds to thousands of polyps throughout the colon by their 30s, and have an almost 100% chance of developing colorectal cancer. People with this condition can be identified with a genetic screening blood test. If positive, immediate family members should be screened. Yearly screening with sigmoidoscopy beginning at age 10 or 12 is recommended.¹ After polyps are detected, surgery to remove the colon (colectomy) should be done to prevent cancer from developing.

Hereditary nonpolyposis colon cancer (HNPCC)

People who have hereditary nonpolyposis colon cancer (HNPCC) may develop colon polyps at an early age. Experts recommend that people with HNPCC have a colonoscopy every 1 to 2 years starting at age 20 to 25, or 10 years younger than the age at which the youngest family member who has colorectal cancer was diagnosed, whichever comes first. HNPCC is also sometimes known as Lynch syndrome.¹