MET amplification in endometrial cancers with clear‐cell carcinoma components

: Endometrial clear-cell carcinoma (ECC) is relatively rare. The expression of diagnostic markers in this disease is similar to that of clear-cell carcinoma, but the molecular carcinogenic events and therapeutic targets are mostly unknown. MET gene amplification has been reported in various cancers, including ovarian clear-cell carcinomas; however, the MET gene status has not previously been examined in ECC. We performed real-time quantitative PCR (QPCR) and fluorescence in situ hybridization (FISH) to analyze the MET gene statuses of 12 ECC cases. We found MET amplifications in two cases (2/12; 16.7%) by both methods. Of the 12 cases, 9 were pure clear-cell carcinomas, and 3 were mixed types that included mixes with endometrioid carcinomas in 2 cases, and the remaining case was a heterologous-type carcinosarcoma that primarily consisted of a clear-cell carcinoma component and a scarce chondrosarcoma component. Both of the MET amplification cases were mixed; one contained endometrioid features, and the other chondrosarcoma features. This is the first report to analyze the statuses of the MET gene in ECCs, and the two mixed cases exhibited amplifications that are shared with ovarian clear-cell carcinomas. Further studies with larger numbers of cases are necessary to reveal the relationship between ECC and MET amplification.