Mismatch repair protein deficiency assessed by immunohistochemistry in sporadic colorectal carcinoma

Context: Globally, colorectal carcinoma (CRC) ranks the third most commonly diagnosed malignant disease, one of the leading causes of cancer deaths. Aims: To study the spectrum of clinicopathological characteristics of sporadic colorectal carcinoma and to assess mismatch repair gene deficiency by the expression pattern of the proteins assessed by immunohistochemistry. Setting and Design: Observational study conducted in a tertiary care hospital in West Bengal. Materials and Methods: Fifty-two surgically resected specimens of CRC received from January 2018 to May 2019 were studied for clinical, morphological, MSI status. Statistical Analysis Used: IBM SPSS 23. Results: A total of 50% of the cases belonged to younger and 50% to the older population, with male predominance being 53.8%. The most common histologic type was adenocarcinoma (88.5%). The majority was found to be well-differentiated carcinoma (50%). The majority cases were of the T3 stage accounting to 38.5%. A total of 24 out of 52 cases (46.15%) had an absent expression of at least one mismatch repair (MMR) protein. A significant correlation was found between the young age group and microsatellite instability (MSI) with a P value of 0.001. A significant association was found between MSI and tumor differentiation with P value of 0.018. A significant association was found between MSH6 and histological type with P value of 0.012. A significant association was found between MSI and tumor stage with P value of 0.032. Conclusions: This study shows a significantly higher number of sporadic colon cancers involving the young age group, and younger cases showed significant association with MSI. This alarming trend needs validation by studies involving larger populations and can be helpful prognostically as well as in formulating chemotherapeutic regimens.