The relationship of microsatellit instability and prognostic factors in endometrium Cancer cases

Introduction and Aim: Endometrial Cancer is the most common gynecological malignancy in developed countries. In our study, it was aimed to examine the effect of microsatellite instability (MSI) on the prognosis and treatment response of the disease in cases with endometrial cancer admitted to our hospital by immunohistochemical methods. Materials and Methods: 204 patients diagnosed with endometrial cancer between 2018 and 2022 were included. Microsatellite instability was investigated by immunohistochemical methods using MLH1, MSH2, MSH6 and PMS2 markers. Patients with instability in at least one locus were considered as MSI, and patients without instability were considered as MSS (microsatellit stable). These two groups were compared in terms of prognostic factors and chemotherapy response. Results: When 204 patients diagnosed with endometrial cancer were examined in our study, the mean age was 61.46 (±10.48). Of the patients, 55 (26.96%) were found to be MSI, and 149 (73.04%) were MSS. The most common loss of expression was observed as mlh-1/pms-2. It was found statistically significant that the stage at the time of diagnosis was higher in patients with MSI than in patients with MSS (p<0.001). When the patients grade, myometrial invasion, lymphovascular invasion and lymph node metastases were evaluated, these parameters were found to be statistically significantly higher in MSI patients compared to MSS patients (p<0.001). The following responses were observed in 11 patients who received chemotherapy, 72.7% complete response, 9.1% partial response, 9.1% stable disease, 9.1% progression. In 13 MSI patients who received chemotherapy, 7.7% had complete response, 46.2% partial response, 15.4% stable disease and 30.8% progression were determined. Conclusion: In our study, it has been shown that microsatellite instability is associated with poor prognostic factors and we think that it can be used as a prognostic marker in the future and MSI patients may be ideal patients for immunotherapy because they respond worse to chemotherapy. Keywords: Endometrial cancer, microsatellite instability (MSI), microsatellite stable (MSS), prognostic factors, chemotherapy response