Genetic predisposition to colorectal cancer: Where we stand and future perspectives

Table 3 Clinical characteristics of familial adenomatous polyposis

Clinical characteristics
Hundreds to thousands of colonic adenomatous polyps (on average beginning at age 16 yr)1
Colorectal cancer (100% penetrance if not treated; average age 39 yr)1
Other gastrointestinal polyps and malignant lesions:
Fundic gland polyps in the stomach
Adenomatous polyps in the stomach and small bowel
Periampullary carcinoma
Duodenal cancer
Congenital hypertrophy of the retinal pigmented epithelium (CHRPE)
Other less common manifestations:
Embryonal tumors (hepatoblastoma and medulloblastoma)
Pancreatobiliary carcinoma
Papillary thyroid carcinoma (especially cribriform-morular variant)
Adrenal cortical tumors
Gardner syndrome subtype (specific characteristics):
Colonic adenomatous polyposis
Desmoid tumors
Epithelial inclusion cysts
Osteoid osteomas
Supernumerary and/or impacted teeth
CHRPE
Turcot syndrome subtype (specific characteristics):
Colonic adenomatous polyposis
Tumors of the central nervous system (medulloblastoma)

¹AFAP: Patients have 10-100 colorectal adenomas. Polyps develop preferentially in the proximal colon, and the onset of colorectal cancer (CRC) occurs 10-15 years later than in patients with classic familial adenomatous polyposis. The cumulative risk of CRC by age 80 years is estimated to be approximately 70%.