Bostancı, Meriç EmreMollaoğlu, Murat CanÖzer, HaticeKaradayı, Kürsat2024-10-262024-10-2620220365-81041307-5608https://doi.org/10.4274/atfm.galenos.2022.04909https://search.trdizin.gov.tr/tr/yayin/detay/1136236https://hdl.handle.net/20.500.12418/24746Objectives: Colorectal cancer is known as the third most common type of cancer worldwide. The microsatellite instability (MSI) pathway is effective in the development of 15-20% of colorectal cancers. MSI is mainly caused by mutational inactivation of one of the four main MMR genes (MSH2, MLH1, MSH6 or PMS2). This study was planned to investigate clinicopathological features of MSI in colorectal cancer and its effect on prognosis. For this purpose, demographic and clinicopathological data of patient groups with MSI and microsatellite stability (MSS) were compared. Materials and Methods: In this study, the pathology reports of 109 patients who were diagnosed with colorectal cancer and were operated on between 01.01.2015 and 01.01.2019 in the Surgery Oncology Clinic of Cumhuriyet University Medical Faculty Hospital were analyzed retrospectively. MLH-1, MSH-2, MSH-6, and PMS-2 antibodies were evaluated together with demographic and histopathological features and survival time of the patients. Results: The histological grade distribution difference between the MSS and MSI groups was not statistically significant (p=0.838). Mostly observed T-stage was T3 in both groups, and the differences between the groups were not statistically significant (p=0.405). Regarding the N stage, N0 was more common in MSS and N2 in MSI; however, no significant difference was observed between the two groups (p=0.844). Lymphovascular invasion (LVI) was not observed in most cases in both groups, and the differences between the groups were not statistically significant (p=0.493). Perineural invasion (PNI) was present in most cases in both groups, and the differences between the groups were not statistically significant (p=0.987). Survival rates according to the groups were evaluated using the Kaplan Meier test, and no statistically significant difference was found in the 2-year survival rates (p>0.05). Conclusion: In this study, the relationship of MLH1, MSH2, MSH6, and PMS2’s immunohistochemical expression with clinicopathological parameters and survival in patients with colorectal cancer was investigated. According to study results, the losses of expression in the cases were 13.7% for MLH1, 9.1% for MSH2, 12.8% for MSH6, and 14.6% for PMS2. Although it was not statistically significant in the study, we think that the survival rate is higher in cases with MSI. However, there was no statistical difference in MSI in terms of gender, age, grade, localization, LVI, and PNI. More parameters should be studied to detect MSI.en10.4274/atfm.galenos.2022.04909info:eu-repo/semantics/openAccessArticle7533553481136236