Screening for hereditary cancers in patients with endometrial cancer reveals a high frequency of germline mutations in cancer predisposition genes.

As inherited genetic alterations are important etiological factors causing endometrial cancer (EC), our study aimed to outline the ethnic-related prevalence and the associated clinical and biological characteristics of germline mutations in cancer predisposition genes in Chinese EC patients. One hundred ninety-eight Chinese EC patients were screened for germline mutations in a panel of cancer susceptibility genes using next-generation sequencing combined with multiplex ligation-dependent probe amplification. First, we found that among patients under 50 years of age, 26% (18/69) carried germline genetic mutations, all involving mismatch repair (MMR) genes except for one mutation affecting BRCA1. Second, when we focused on Lynch syndrome (LS) with additional selected patients, 45 were identified to carry pathogenic mutations in MMR genes, with a higher frequency found in MSH2 and MSH6. We found that age at onset, personal and familial history together with immunohistochemical assay results were the most useful criteria for the diagnosis of LS although limitations in routine practice and the sensitivity and specificity of each parameter should be taken into account. One pathogenic mutation in the PALB2 gene was detected in a patient with no breast cancer in her family. Interestingly, we identified a family carrying pathogenic variant in both PMS2 and BRCA1 genes with distinct clinical phenotypes. Multigene panel testing should be recommended to patients based on their clinical information and tumor phenotype. Our study also showed the genetic complexity in EC, which requires further investigations.