Mismatch repair in patients diagnosed with ovarian cancerthe effect of the mutation in their genes on the prognosis

PURPOSE: The aim of our study was to determine the rate of DNA mismatch repair (MMR) gene defects in ovarian malignancies by examining DNA mismatch repair (MMR) gene defects in ovarian tumours, to determine whether these mutations differ according to histological types, and to determine whether these mutations have an effect on the prognosis of ovarian cancer and whether they have an effect on recurrence and survival according to types. MATERIALS AND METHODS: n our study, 40 ovarian cancer cases in the archive of Celal Bayar University Department of Pathology, which were regularly followed up between 1 January 2008 and 30 December 2023 in the Gynaecology and Obstetrics Department of our hospital, were evaluated. Of these, 2 patients were excluded from the study because their pathological slides were not available. The clinical course (life expectancy from the time of diagnosis, final status, etc.) was determined from the patients' files. In block selection, care was taken to select areas free of necrosis. Then, MLH1, PMS2, MSH2 and MSH6 immunohistochemical stains for mismatch repair (MMR) genes were performed to determine microsatellite instable (MSI) tumours. RESULTS: Of the cases, 27 were high grade serous carcinoma, 6 were endometrioid carcinoma and 2 were clear cell carcinoma. Immunohistochemical examination of pathological preparations revealed MMR gene loss in 2 cases. In 1 case MLH1 and PMS2 and in 1 case MSH2 and MSH6 MMR gene loss was detected. MMR protein defect was found in 5.2% of ovarian cancer cases. MMR protein defect was seen in 33.3% of endometrioid type ovarian cancer, but not in serous type ovarian cancer. CONCLUSION: In our study, MMR gene defect was seen in 33.3% of the Endometrioid type, and it would be more meaningful to examine MMR gene defect in these histological types. Studies with a larger case population are needed to evaluate the effect of MMR gene defect on prognosis. KEYWORDS: Ovarian cancer, Mismatch repair, Endometrioid type, Microsatellite instability