Association of clinicopathological features with DNA mismatch repair status among colorectal cancer patients presenting to a Tertiary Care Cancer Hospital

Abstract

Background: About 12%–15% of sporadic colorectal cancers (CRCs) display a defect in the DNA mismatch repair (MMR) system resulting in microsatellite instability (MSI). Many authors have described certain clinicopathological predictors of MSI and confirmed with ancillary studies. The purpose of this study was to determine the clinicopathological features and their association with MMR deficiency (dMMR) among CRC patients. Materials and Methods: A cross-sectional study was designed among patients presented with CRC. A predesigned proforma was used to document the particulars of the patient along with histological parameters to be assessed. Cases were analyzed for dMMR using MLH1 and MSH2 immunostains and categorized into dMMR and MMR-proficient. The association of clinicopathological features with MMR status was statistically analyzed. Results: Sixty-four CRC cases were analyzed in the study. Thirteen out of 64 cases showed dMMR. Most of the dMMR tumors were located in the right-sided colon (P < 0.001). Three patients with a family history of CRC exclusively had dMMR (P = 0.01). Mucinous (P = 0.04), signet ring cell differentiation (P = 0.04), and lack of dirty necrosis (P < 0.001) showed a significant difference between deficient and proficient MMR categories. Gender, mean tumor-infiltrating lymphocytes per hpf, Crohn's-like reaction, and tumor stage did not show any significant difference between the two categories. Conclusions: Clinicopathological features such as family history, tumor location, tumor size, histologic type, tumor differentiation, mucinous, signet ring cell component, and dirty necrosis are associated with MMR status in CRC.