Polyps and inherited gastrointestinal cancer syndromes: Viva

Branch 1: Framing the family history and the first question

A strong candidate reframes the consultation as one about an inherited cancer syndrome rather than a single symptom. Familial adenomatous polyposis is an autosomal dominant APC disorder in which hundreds to thousands of adenomas develop, with near-certain colorectal cancer without colectomy, so the key immediate step is to confirm whether the father carries a known pathogenic APC variant. The candidate should take a full three-generation family tree, asking about early colorectal, gastric, pancreatic, breast, and gynaecological cancer, desmoid tumours, and hepatoblastoma, and establish whether the father has had germline testing. [1]

The candidate should then state clearly that the daughter has a one in two chance of inheriting the mutation, and that the correct management is predictive genetic testing once the family variant is identified, rather than blind endoscopy of every at-risk child. Counselling, the child's assent, and referral to a familial cancer service precede testing, because a positive result is the gate that opens surveillance and a negative result allows the child to avoid it. [3]

Branch 2: Surveillance, surgery, and the desmoid trap

If the examiner asks what happens if the girl tests positive, the candidate should set out the age-based surveillance. At-risk children undergo flexible sigmoidoscopy from the early to mid-teens, moving to colonoscopy once adenomas appear, with the aim of controlling the polyp burden endoscopically and timing prophylactic colectomy before cancer develops. Surgery is usually planned in the late teens to mid-twenties, when the polyp load or dysplasia outstrips endoscopic control, and the options are a total colectomy with ileorectal anastomosis or a proctocolectomy with ileal pouch-anal anastomosis, chosen according to the rectal polyp burden and the family desmoid risk. [1]

A discriminating candidate then volunteers the desmoid pitfall. Desmoid tumours are locally invasive fibroproliferative masses that are provoked by surgical trauma, recur aggressively, and are a leading cause of death in familial adenomatous polyposis. A strong family history of desmoids therefore pushes the surgical choice towards minimising further operations and away from premature surgery. The candidate should also mention upper gastrointestinal surveillance for duodenal adenomas in adulthood and the coordinated transition to adult care. [1]

Branch 3: Broadening to the syndromic picture

If the examiner widens the discussion, the candidate should place familial adenomatous polyposis among the inherited polyposis syndromes and contrast it cleanly. Juvenile polyposis is hamartomatous, defined by more than five juvenile polyps, and caused by SMAD4 or BMPR1A, with a roughly forty per cent colorectal cancer risk and an overlap with hereditary haemorrhagic telangiectasia. Peutz-Jeghers is STK11, with characteristic lip and buccal pigmentation, small-bowel hamartomatous polyps that intussuscept in childhood, and the highest overall lifetime cancer risk, including feminising Sertoli-cell tumours in boys. MUTYH-associated polyposis is the autosomal recessive exception. A complete answer finishes by stressing that every suspected syndrome is referred to a familial cancer service for germline diagnosis, predictive testing of relatives, and lifelong multidisciplinary surveillance. [2]