Immunohistochemical evaluation of microsatellite instability in colon polyps and colorectal cancers

Abstract

Objective: Colorectal cancers (CRCs) are among the most common malignancies. In 15% of these cases, there is a defect in the DNA mismatch repair pathway, which results in microsatellite instability (MSI). Conventional adenomatous lesions considered the precursors of CRCs also show MSI. Detection of MSI in adenomas is useful for early diagnosis of Lynch Syndrome. MSI is detected by molecular study. We attempted to immunohistochemically evaluate the MSI in colon cancer and polyps. Design: Retrospective study Setting: Department of Pathology, Mugla Sıtkı Kocman University Training and Research Hospital, Turkey Subject: We performed immunohistochemical MSI analysis of 119 colon polyps and 88 conventional CRC patients who had materials in our hospital pathology laboratory between 2014 and 2017. For this purpose, the immune markers MLH1, MSH2, PMS2 and MSH6 were used. All statistical analyses were done with the SPSS 14.0 software. Paired comparisons were performed using the Independent Sample t test and one sample t test. P<.05 was considered statistically significant. Intervention: None Main outcome measures: MLH1, MSH2, PMS2 and MSH6 immunhistochemical markers of MSI and colon lesions Results: We detected MSI in tubular and tubulovillous adenomas with high dysplastic content (P=.05) and left colonic localization (P=.05). We detected MSI predominanlty in female patients (P=.05), tumors with right colonic localization (P=.05), larger tumors (P=.05), advanced stage tumors (P=.05), and tumors with lymph node metastases (P=.05). Conclusion: According to our findings, immunohistochemical MSI analysis may have a decisive role prior to molecular analysis in early colorectal lesions and CRCs. © 2020, Kuwait Medical Association. All rights reserved.