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]