Mismatch repair proteins evaluation in endometrial carcinoma: clinicopathological features and prognostic implications

Endometrial carcinoma is a prevalent cancer affecting women worldwide. Mismatch repair proteins (MMR) play a crucial role in maintaining genomic stability and preventing the accumulation of mutations. The evaluation of MMR proteins can aid in the identification of mismatch repair deficient (MMRd) tumors, which have distinct clinicopathological features and prognostic implications. This study aims to analyze the expression of MMR proteins in a cohort of 96 endometrial carcinoma cases collected from the pathology department archive at a tertiary center between 2010 and 2022. Of the 96 cases, 36 were classified as MMRd, which encompassed various subtypes, including endometrioid, mixed mullerian tumor (MMMT), and papillary serous carcinoma. The MMRd tumors exhibited distinct histopathological characteristics, such as low-grade differentiation and lymphoepithelioma-like patterns. Immunohistochemical analysis revealed paired loss of MLH1 and PMS2 in the majority of cases, while loss of MSH2 and MSH6 was observed in a smaller subset. Additionally, in a subset of patients had a familial history of cancer, indicating potential hereditary factors contributing to MMRd. In terms of prognostic markers, MMRd tumors exhibited higher rates of Estrogen Receptor (ER)/Progestron Receptor (PR) positivity and wild type p53 staining. Overall, our findings suggest that the evaluation of MMR proteins in endometrial carcinoma can provide valuable insights into the clinicopathological characteristics and prognostic implications of MMRd tumors.