<prompt> In a FAP patient which is an important CA riskRetinoblastomaBrain tumorColorectal CAProstate CA  <response>: Ref: Robbins Pathology, 9th ed. pg. 809 Familial adenomatous polyposis FAP is an autosomal dominant disorder in which patients develop numerous colorectal adenomas as teenagers. Robbins states: Colorectal adenocarcinoma develops in 100 of untreated FAP patients, often before age 30 and nearly always by age 50 As a result, prophylactic colectomy is the standard therapy for individuals carrying APC mutations. Colectomy prevents colorectal cancer, but patients remain at risk for neoplasia at other sites. FAP is also associated with a variety of extraintestinal manifestations: Congenital hypertrophy of the retinal pigment epithelium Gardner syndrome and Turcot syndrome 