NEJM Knowledge+ - Question of the week

A 39-year-old man was admitted for a bowel obstruction and found to have a large obstructing colonic adenocarcinoma just proximal to the hepatic flexure. He underwent a successful right hemicolectomy. Pathology was consistent with an obstructing, 9-cm colon adenocarcinoma, with no evidence of lymph node involvement in 17 sampled nodes.

When asked about his family history, the patient states that his mother and maternal aunt were diagnosed with endometrial cancer at ages 56 and 59, respectively. His mother has no other siblings, but her father died in his early 40s of an unknown cause after several months of worsening abdominal pain and weight loss. The patient has two younger siblings and three children, all of whom are healthy.

What is the most likely underlying diagnosis in this case? » Peutz–Jeghers syndrome » Familial adenomatous polyposis (Gardner's syndrome) » BRCA » Hereditary nonpolyposis colorectal cancer (Lynch syndrome) » Li–Fraumeni syndrome