Comparison of Clinical and Histopathological Parameters amongst Microsatellite Unstable and Microsatellite Stable Cases of Colorectal Carcinomas in an Indian Setting

Abstract

Introduction: In this era of prognosis based medicine, it is important to identify microsatellite unstable Colorectal Cancers (CRCs) as they offer good prospects to the patient and they respond poorly to 5-fluorouracil and platinum based chemotherapeutic regime. Aim: To find out the prevalence of Microsatellite Instability-High (MSI-H) in CRC, to identify clinicopathological features associated with Microsatellite Instability (MSI) and assess the value of surgical pathology in predicting MSI-H. Materials and Methods: The present study was a case-control study conducted in a tertiary care centre of Pune in Western India from January 2013 to December 2020. Thirty-five CRCs deficient in Mismatch Repair (MMR) proteins contrasted with 206 Microsatellite Stable (MSS) CRCs were studied and analysed for a given set of clinical and histopathological parameters to find out any correlation between the occurrence of microsatellite unstable tumours and these variables were presented as percentages. Results: In the present study, the prevalence rate of MSI-H was found to be 14.5% and the statistical analysis was carried out using the software Statistical Package for the Social Sciences (SPSS) version 27.0. Univariate analysis revealed that right-sided/proximal location of tumours, age at diagnosis less than 50 years, no lymph node deposits (N0 disease), presence of Tumour Infiltrating Lymphocytes (TILs), peri-tumoural reaction, mucinous component, increased stromal plasma cells, histological heterogeneity, signet ring/medullary component and Crohn-like reaction were all statistically significant predictors of microsatellite instability (p-value <0.05). Multivariate analysis of these significant parameters revealed right-sided location of tumours, age at diagnosis less than 50 years, N0 disease, and presence of TILs, increased stromal plasma cells, histological heterogeneity and Crohn-like reaction to be independent predictors. Conclusion: Clinical parameters and histological evaluation is handy in screening for the MSI-H colorectal carcinomas. This would go a long way in selecting the patients who will require confirmatory molecular testing and thus precluding the need of Immunohistochemistry (IHC), which will be helpful in day-to-day practice as it is uncomplicated, cost-effective and easy to replicate.

Keywords

• deoxyribonucleic acid mismatch repair
• immunohistochemistry
• microsatellite instability