Polyps may also grow in the stomach, duodenum, spleen, kidneys, liver, mesentery, and small bowel.

[5] There is no cure at this time, and in its more advanced forms, it is considered a terminal diagnosis with a life expectancy of 35–45 years; treatments are surgery and palliative care, although some chemotherapy has been tried with limited success.

[3] This gene is also mutant in familial adenomatous polyposis (FAP), a more common disease that also predisposes to colon cancer.

Gardner syndrome is set apart as a subtype because, in addition to colonic polyps, there are also extra-colonic growths (both malignant and benign).

Gardner syndrome is also associated with familial adenomatous polyposis and may manifest as aggressive fibromatosis (desmoid tumors) of the retroperitoneum.

[11] Desmoid tumors arise most frequently from the aponeurosis of the rectus abdominal muscle of multiparous women.

Treatments for desmoid tumors may include surgery, NSAIDS, anti-estrogen medications, radiation therapy and chemotherapy.