Although familial adenomatous polyposis (FAP) is associated with an increased risk of colon and rectal cancer, other problems outside the colon and rectum may develop. As a result, it is important to be aware of all of the risks of FAP and the methods used to screen for them – routine and timely screening is of the upmost importance in catching cancers and other problems early so they can be successfully treated.

Risks of FAP

What follows is a list of the common problems that you may encounter if you have been diagnosed with FAP; the number in parenthesis shows how common each condition is and represents the percentage of all FAP patients who will develop the condition.

Colon/Rectal Polyps (100 percent) and Colon/Rectal Cancer: Colon polyps, a type of pre-cancerous polyp known as adenomas, are found in every FAP patient. The number of polyps may vary from less than 100 to thousands. Screening endoscopy and ultimately removal of the colon and/or rectum prevents these polyps from developing into cancer. If the polyps are not removed, the risk of cancer is 100 percent.

Upper Gastrointestinal (GI) Adenomas (95 percent): Polyps can also be found in the stomach and small intestine. These can be benign polyps or pre-cancerous polyps. These polyps can generally be removed with timely screening endoscopies but occasionally may require an operation. If left unchecked, these polyps can progress to cancer. Five percent of FAP patients develop cancer in the small intestine or stomach from these polyps.

Desmoid Tumors (15 percent): Desmoids are a type of fibrous tumor usually found in the abdomen (although they can develop anywhere in the body). This type of tumor can cause problems by growing into vital organs in the abdomen and compromising the blood supply to the intestine.

Thyroid Cancer (1 percent): The thyroid is a small glandular organ found in the neck. Although a 1 percent incidence may not seem like a lot, the risk of thyroid cancer is approximately 179 times greater for men with FAP and 61 times greater for women with FAP than in the general population. (Source: National Cancer Institute)