Colon polyps and polyposis

FAP is a hereditary condition caused by mutations in the APC gene, a gene that helps control how cells grow and die. When the APC gene is not working properly, hundreds to thousands of adenomatous polyps (growths made of gland-like tissue) can form in the colon, often beginning in the teenage years. Without close monitoring and polyp removal, people with FAP have a very high risk of colorectal cancer. Polyps may also appear in the stomach and small intestine.

• Classic FAP is characterized by hundreds to thousands of colon polyps starting in adolescence.
• Attenuated FAP (AFAP) involves fewer polyps that tend to develop later in adulthood.

MAP occurs when a person inherits two mutations in the MUTYH gene, a gene that helps repair DNA damage in colon cells. When both copies of this gene are not working correctly, multiple adenomatous polyps can form, often beginning in young adulthood. Without treatment or frequent colonoscopy, the risk of colon cancer is significantly higher.

These rare conditions involve distinctive hamartomatous polyps, tumor-like growths made of a mix of normal tissues arranged in an unusual way, which may appear throughout the GI tract. Although these polyps are benign, the related syndromes carry an increased risk of cancers in the digestive system and sometimes in other organs.

Conditions in this group include:

• Peutz-Jeghers syndrome
• Juvenile polyposis syndrome
• Cowden syndrome (also called PTEN hamartoma tumor syndrome)

SPS is marked by multiple serrated polyps, a group of polyps with a saw-toothed appearance. These can raise the risk of colon cancer. Because SPS patterns can vary, people with this syndrome benefit from specialized surveillance.

This diagnosis is used when someone develops more than 20 adenomatous polyps over a lifetime but no genetic syndrome is identified through testing. Even without a known cause, these individuals still need careful monitoring because their risk of colon cancer is higher.