The Lynch syndrome (hereditary non-polyposis colorectal cancer, HNPCC) associated endometrial cancer is characterised by which of the following features?

• A BRCA1 mutation, oestrogen-dependent Type 1 carcinoma, and excellent prognosis
• B Mismatch repair gene defect, younger age at onset, and synchronous ovarian cancer in up to 10% of cases ✓
• C Microsatellite stability and association with Lynch syndrome
• D TP53 mutation, high-grade serous histology, and Type 2 biology

Explanation

Lynch syndrome is caused by germline mutations in mismatch repair (MMR) genes (MLH1, MSH2, MSH6, PMS2), resulting in microsatellite instability (MSI-high). Endometrial cancer is the most common Lynch-associated extra-colonic malignancy, occurring at a mean age of 48 years (younger than sporadic cases). Synchronous ovarian and endometrial carcinoma occurs in ~8–10% of Lynch-associated cases. Type 2 endometrial cancer (serous) is associated with TP53 mutations and oestrogen-independent pathogenesis. BRCA mutations are associated with ovarian and breast cancer, not primarily endometrial cancer.

Reference: Shaw's Textbook of Gynaecology, 17th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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