Abstract:

Objective We aimed to evaluate the correlation between the immunohistochemical expressions of MLH1, PMS2, MSH6, MSH2 and clinicopathological parameters in gastric carcinoma. Matherials and Methods Immunohistochemistry was performed on the tissue microarray (TMA) sections of 103 primary gastric adenocarcinoma and 27 gastric mucosal tissue samples without tumor. All markers were evaluated for the presence of nuclear staining. Negative expression in any of the markers was accepted as a deficiency. Then, the comparison was made between the two subgroups as; deficient mismatch repair (dMMR) and proficient mismatch repair (pMMR). Results The histopathological subtypes as intestinal and non-intestinal, the intestinal group showed significant deficient expression of MSH2 compared with the non-intestinal group. PMS2 expression was significantly higher in the other subtypes than signet ring cell carcinoma. Also, we observed that the loss of MLH1 and PMS2 expressions were higher in moderately/ poor differantiated tumors than the well differantiated ones. Perineural invasion was significantly higher in patients with loss of MLH1, MSH6, PMS2 expression and dMMR compared to patients with pMMR. There was no significant difference between dMMR and pMMR when compared the groups who received chemotherapy/ radiotherapy and who did not. There was not found significant relationship between MLH1, MSH2, MSH6, PMS2 expressions and survival. Conclusion We found a significant relationship between perineural invasion and the loss of expression of MLH1, MSH6 and PMS2. PMS2 expression was also significantly higher in the other subtypes of GC than signet ring cell carcinomas.

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