MDM4 amplification as a potential predictor of risk of recurrence in early-stage low-grade endometrial carcinoma

OBJECTIVE: This study aimed to assess the frequency of MDM4 amplification in endometrial carcinomas and its association with clinicopathological features, particularly relapse risk in early-stage low-grade endometrioid endometrial carcinoma. METHODS: We conducted a case-control study including 110 stage I to II low-grade endometrioid endometrial carcinomas (39 relapsing and 71 non-relapsing tumors) and an additional cohort of 82 high-grade endometrial carcinomas. An independent retrospective cohort of 194 early-stage low-grade endometrioid endometrial carcinomas was used to validate the results. MDM4 amplification was analyzed by fluorescent in situ hybridization. Gene expression of MDM4 and GADD45A was measured by quantitative real-time polymerase chain reaction. Immunohistochemistry assessed hormone receptor status, p53, and mismatch repair proteins. POLE and CTNNB1 mutations were evaluated by Sanger sequencing. RESULTS: MDM4 amplification was detected in 31 of 186 tumors (16.7%): 14 of 104 low-grade endometrioid endometrial carcinomas (13.5%) and 17 of 82 high-grade endometrial carcinomas (20.7%). Among low-grade endometrioid endometrial carcinomas, amplification was significantly more frequent in relapsing tumors (11/38, 28.9%) than in non-relapsing ones (3/66, 4.5%) (p