Investigation of the Relationship Between Immunohistochemical Mismatch Repair (MMR) Protein Expression and Prognostic Parameters in Endometrial Carcinomas

Abstract

Objective: Molecular classification has been the most important development in endometrial carcinomas in recent years. This classification divides tumors into four groups: (i) POLE mutant group, (ii) microsatellite instable (MSI) group, (iii) high copy number group (P53 mutation), and (iv) low copy number group. Among these groups, POLE and MSI groups stand out with their better prognosis and potential to benefit from immune-control inhibitor therapy. In our study, we aimed to compare the prognostic parameters of patients with and without nuclear expression loss in MMR proteins (MLH-1, PMS-2, MSH-2, MSH-6) by immunohistochemical (IHC) method. Methods: Between 2017 and 2020, 80 patients who were diagnosed with endometrial carcinoma in hysterectomy material and whose MMR proteins were evaluated as IHC were included in the study. Patients with and without MMR loss were compared in terms of tumor size, histological grade (HD), depth of myometrial invasion, lymphovascular invasion (LVI), and cervical involvement. Results: Loss of any of the MMR proteins was present in 37 cases (46.3%), while 43 cases (53.7%) had no loss. When the cases were compared in terms of loss of MMR protein nuclear expression, 45.9% (17/37) of the cases with loss and 27.9% (12/43) of the cases without loss had histologic grade III (P = 0.03). There was no statistically significant difference between the two groups in terms of myometrium 1/2 external invasion, cervical stromal involvement, and LVI. Conclusion: Approximately half of the patients in our study lost at least one of the MMR proteins. The most common losses were MLH-1 and PMS-2. The HD of patients with loss of nuclear expression of MMR proteins tended to be statistically significantly higher than those without loss.