A comparison of microsatellite instability with clinicopathological data in colon adenocarcinoma

Colorectal cancers are the third most common in both sexes and they are the second most common cause of cancer-related death. 12-15% of colorectal cancers develop through microsatellite instability pathway and they are 2-5% hereditary. This pathway include the hereditary mutation in at least one of DNA mismatch repair genes (MLH-1, PMS-2, MSH-2, MSH-6). In this study, we investigated the correlation between the clinicopathological features and the immunohistochemical MLH-1, MSH-2, PMS-2, MSH-6 expressions in a total of 116 resection materials with colorectal adenocarcinoma between 2014 and 2016. All the cases were retrospectively evaluated in terms of age, sex, size, histologic grade, lymphovascular and perineural invasion, distant metastasis, localization, border, dirty necrosis, tumor infiltrating lymphocytes, Crohn-like response, mucinous and medullary differentiation, tumor budding, clinical stage, pathological tumor stage, and lymph node metastasis. Immunohistochemistry stained sections of the all patients were reevaluated retrospectively. MLH-1, MSH-2, PMS-2, MSH-6 primary antibodies were used. We found a positive correlation between loss of MMR protein expressions and the right-colon location, greater tumor size, pushing borders, high histologic grade and dense lymphocytic infiltration. We found a correlation between immunohistochemical markers and clinicopathological features usually observed in tumors with microsatellite instability. This finding may arouse suspicion for MSI. However, the findings in our study must be supported with including molecular methods.