Original article / research
Year : 2026 Month : April Volume : 15 Issue : 2 Page : PO15 - PO20 Full Version

Mismatch Repair Protein Expression and its Association with Clinicopathological Parameters in Colorectal Carcinoma: A Cohort Study
Mouli Mishra, Akruti Mishra, Sabyasachi Parida, Suravi Mohanty
1. Postgraduate Trainee, Department of Pathology, Kalinga Institute of Medical Sciences KIIT University, Bhubaneswar, Odisha, India. 2. Assistant Professor, Department of Pathology, Kalinga Institute of Medical Sciences KIIT University, Bhubaneswar, Odisha, India. 3. Senior Consultant, Department of Surgical Oncology, Kalinga Institute of Medical Sciences KIIT University, Bhubaneswar, Odisha, India. 4. Professor, Department of Pathology, Kalinga Institute of Medical Sciences KIIT University, Bhubaneswar, Odisha, India.
 
Correspondence Address :
Suravi Mohanty,
Chitrakala, Jhanjirimangala, Cuttack-753009, Odisha, India.
E-mail: drsuravimohanty@gmail.com
 
ABSTRACT
: Introduction: Colorectal Carcinoma (CRC) ranks third in global cancer prevalence and is a major cause of cancer-related deaths. The pathogenesis of CRC involves complex genetic and molecular alterations, notably defects in the Deoxyribonucleic Acid (DNA) Mismatch Repair (MMR) pathway. The MMR system, which includes proteins like MLH1, MSH2, MSH6, and PMS2, corrects DNA replication errors. When deficient, it results in Microsatellite Instability (MSI), characterised by changes in repetitive sequence lengths, which are key biomarkers in CRC. High-MSI (MSI-H), defined as the deficiency of more than one MMR protein, is clinically significant due to its association with better prognosis, enhanced response to immunotherapy, and its link to Lynch syndrome.

Aim: To evaluate the expression of MMR proteins in CRC and its association with various clinicopathological parameters.

Materials and Methods: This was a cohort observational study conducted at the Department of Pathology, Kalinga Institute of Medical Sciences, Bhubaneshwar, Odisha, India over a period of 24 months from June 2022 to May 2024. A total of 62 histologically confirmed CRC cases were examined using Immunohistochemistry (IHC) to assess MMR protein expression. MSI status was classified into three groups based on MMR protein expression: Microsatellite Stable (MSS) with no loss of expression, MSI-H with the loss of more than one MMR protein, and low MSI (MSI-L) with the loss of one MMR protein. The associations with clinicopathological features such as age, gender, tumour site, size, histological type, grade, Lymphovascular Invasion (LVI), Perineural Invasion (PNI), and lymph node status were analysed using the Chi-square test through Statistical Packages of Social Sciences (SPSS) version 23.0, and results were presented as figures and tables.

Results: Of the 62 cases of CRC, 43 (69.35%) were MSS, 15 (24.19%) were MSI-H, and 4 (6.45%) were MSI-L. MSI-H tumours showed significant associations with right colon location (p=0.04), marked intratumoural lymphocytic infiltration (p=0.003), and peritumoural lymphocytic infiltration (p=0.001), indicating an enhanced immune response. Most patients with MSI-H status survived after a minimum follow-up of six months, with an average survival of 1,752 days, compared to MSS patients, who had an average survival of 1,141 days.

Conclusion: The MMR protein expression assessed by IHC is a reliable method to screen for MSI in CRC. The association of MSI-H with specific histological features, like marked intratumoural and peritumoural lymphocytes and right-sided tumour location, highlights its importance in guiding further genetic testing and management.
Keywords : Colorectal cancer, Immunohistochemistry, Microsatellite instability, Replication errors
DOI and Others : DOI: 10.7860/NJLM/2026/80600.2961 Date of Submission: May 14, 2025 Date of Peer Review: Jun 25, 2025 Date of Acceptance: Aug 18, 2025 Date of Publishing: Apr 01, 2026 AUTHOR DECLARATION: • Financial or Other Competing Interests: None • Was Ethics Committee Approval obtained for this study? Yes • Was informed consent obtained from the subjects involved in the study? Yes • For any images presented appropriate consent has been obtained from the subjects. NA PLAGIARISM CHECKING METHODS: • Plagiarism X-checker: May 15, 2025 • Manual Googling: Aug 11, 2025 • iThenticate Software: Aug 16, 2025 (10%) ETYMOLOGY: Author Origin EMENDATIONS: 7
 
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