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5 slides generated from the cancer page, with a quiz from the open benchmark and speaker notes that cite the sources. Arrow keys move between slides; Print gives one slide per page.
In familial adenomatous polyposis a person inherits a fault in the APC gene and grows hundreds or thousands of polyps in the large bowel from their teens. Left alone, almost all of them become cancer by about 40, so the bowel is watched from childhood and usually removed before that happens; the cancers that do occur are treated like ordinary bowel cancer.
What it is. Familial adenomatous polyposis is an inherited condition caused by a germline variant in APC, the gatekeeper of the Wnt pathway whose loss also opens the sporadic adenoma-carcinoma sequence. Carriers develop hundreds to thousands of colorectal adenomas from adolescence; an attenuated form produces fewer polyps later in life. The World Health Organization lists it among the genetic tumour syndromes of the digestive system. It is not only a bowel condition: duodenal and gastric polyposis occurs in almost all patients, desmoid tumours are a leading cause of death after colectomy, and thyroid cancer, hepatoblastoma and medulloblastoma occur (Nagtegaal 2020; Gastrointest Endosc Clin N Am 2022).
How it differs from its parent. The cancer that arises in polyposis is an ordinary colorectal adenocarcinoma; what differs is everything before and after it. Cancer Research UK records that almost all untreated patients develop bowel cancer by age 40, against a median age at diagnosis of 66 in the United States for colorectal cancer generally. The tumours are the endpoint of a field of hundreds of adenomas rather than of one, which is why segmental resection is rarely enough and why surveillance of the retained rectum or ileal pouch continues for life after surgery (Best Pract Res Clin Gastroenterol 2022).
| Setting | Approach | Guideline |
|---|---|---|
| Surveillance and prophylactic surgery in carriers | Colonoscopy from about age 10 to 12 at one to two-yearly intervals; prophylactic colectomy before cancer develops, with the type and timing decided case by case; lifelong endoscopic surveillance of the retained rectum or ileal pouch afterwards; upper gastrointestinal endoscopy with ampullary visualisation at intervals set by duodenal and gastric findings. | not mapped |
| Cancer arising in polyposis | Staged and treated as colorectal adenocarcinoma of the same stage, with the extent of resection decided by the field of polyps rather than by the single tumour; the parent record carries the systemic therapy rows. | not mapped |