What is FAP, the APC gene, and the standard risk-reducing surgical approach?

• A. Familial adenomatous polyposis due to APC mutations; hundreds to thousands of polyps with near-certain colorectal cancer risk; colectomy with ileal pouch-anal anastomosis.
• B. Lynch syndrome; colonoscopy every year.
• C. Li-Fraumeni; surveillance only.
• D. Cowden syndrome; thyroid removal.

Answer: (A)

Familial adenomatous polyposis is caused by germline mutations in the APC gene, which drives the development of hundreds to thousands of polyps in the colon and rectum. Because the cancer risk with this many polyps is effectively universal if the colon isn’t removed, the standard risk-reducing operation is colectomy with creation of an ileal pouch-anal anastomosis, removing the colon and linking a surgically formed ileal pouch to the anus to maintain bowel function. This approach is the definitive way to prevent colorectal cancer in FAP patients.

The other syndromes describe different inherited cancer risks with distinct management. Lynch syndrome involves mismatch repair gene defects and is typically managed with regular colonoscopy rather than routine early colectomy; Li-Fraumeni carries broad cancer risk managed by comprehensive surveillance rather than a single surgical cure; Cowden syndrome involves PTEN mutations with risks including thyroid cancer, managed with targeted surveillance and treatment as indicated.