Individuals with familial adenomatous polyposis (FAP) have hundreds to thousands of polyps in their colon and rectum by the time they reach 30 to 40 years of age.
These individuals usually have an extremely high lifetime risk to develop colon cancer if the polyps are left untreated. They are also at increased risk for papillary thyroid cancer, pancreatic cancer, medulloblastomas (a specific brain tumor), and stomach cancer.
FAP causes benign tumors, called desmoids, which can damage nearby organs. FAP is also associated with skin cysts, benign bone tumors especially on the scalp and jaw, extra teeth, and CHRPE (extra areas of pigmentation in the eye). Individuals with FAP usually need to have their colon removed.
The risk of cancer can be greatly reduced once someone has been diagnosed with FAP.
Each child of someone with FAP has a 50 percent chance of having FAP. Other relatives are at increased risk as well.