Microsatellite instability (MSI) in endometrial cancer; frequency and prognostic significance

Abstract

Aim: In our study, we aimed to evaluate the frequency of MSI in endometrial cancer and its relationship with prognostic parameters and inflammatory indexes. Material and Methods: MLH1, MSH2, MSH6, and PMS2 mutations were evaluated immunohistochemically in paraffin blocks of 74 patients diagnosed with endometrial cancer. If no staining was detected in any of these proteins, the tumor was considered microsatellite instable (MSI). Demographic and pathological data of the patients were obtained from the file records. Results: MSI was detected in 21 (28.3%) of 74 patients; expression loss of MLH-1 /PMS-2 (18.9%) in 14, PMS-2 (4.03%) in 3, MSH-2 (2.7%) in 2, MSH-6/PMS-2 (1.3%) in 1 and loss of expression of MSH-2/PMS-2 (1.3%) was observed in 1 of them. There was no significant difference between MSS and MSI groups in terms of age, grade, lymph node, stage, LVI, histological subtype. The 5-year survival rates were 73% in the MSS group and 46% in the MSI group, but this difference was not statistically significant (p=0.760). Discussion: In conclusion, in this study, it was determined that MSI status did not affect the prognosis in endometrial cancers. With the widespread use of immunotherapies, the predictive role of knowledge of the MSI status in endometrial cancer comes to the forefront rather than its prognostic value. In addition, knowledge of the MSI status has gained importance in the new molecular classification of endometrial cancer.