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Updated: Sep 3, 2025
Evaluation of Colorectal Cancer Risk and Prevalence by Stool DNA Integrity Detection
Published on: June 8, 2020
Microsatellite instability in colon cancer: A single center experience from North India
Savita Arora1, Narayan Adhikari1, Arun Kumar Rathi1
1Department of Radiotherapy, Maulana Azad Medical College, Lok Nayak Hospital, New Delhi, India.
Background:
Due to the defects of mismatch repair (MMR) genes MLH1, PMS2, MSH2, and MSH6, the mutations which occur in microsatellite region are not repaired during deoxyribonucleic acid synthesis, leading to microsatellite instability (MSI). MSI is one of the major molecular changes that occur in colorectal carcinoma (CRC). Studies have shown that MMR deficient CRC has different clinicopathological characteristics and a better stage adjusted survival when compared to microsatellite stable tumors.
Materials And Methods:
We have retrospectively analyzed the cases of colon cancers treated in our institute for 3 years from 2017 to 2019. Most of the patients underwent surgery and received adjuvant chemotherapy. MSI testing was done in surgical specimen with immunohistochemistry. The clinical details of the patients were tabulated in Microsoft Excel, and statistical analysis was done using IBM SPSS Statistics for Windows, version 21 (IBM Corp., Armonk, NY, USA).
Results:
A total of 52 patients who were treated in our institution from 2017 to 2019 were analyzed. The mean age was 46.8 ± 13.5 (19-72) years. The male-to-female ratio was 8:5. No significant association in patient demographics and clinicopathological parameters was observed between MSI stable and unstable disease. However, lymphovascular invasion showed a significantly higher trend in MSI unstable patients (P = 0.052). The median progression-free survival (PFS) of the entire cohort was 27.8 months (95% confidence interval = 22.7-32.9) and the median overall survival (OS) is not reached. The median PFS is 21.3 months in MSI stable patients whereas it is not reached in MSI unstable patients (P = 0.049). The median OS is 27.1 months in MSI stable patients, but it is not reached in MSI unstable patients and the difference shows a trend towards statistical significance (P = 0.061).
Conclusion:
MSI unstable tumors were found to have higher PFS and higher OS in our study. It needs prospective validation in larger studies in Indian scenario.
Insights
Microsatellite instability (MSI) in colorectal cancer patients indicates better progression-free survival and overall survival. This finding suggests MSI may be a positive prognostic biomarker in Indian colorectal cancer cases.
Area of Science:
- Oncology
- Molecular Biology
- Genetics
Background:
- Microsatellite instability (MSI) arises from unrepaired DNA synthesis errors in mismatch repair (MMR) genes (MLH1, PMS2, MSH2, MSH6).
- MSI is a key molecular alteration in colorectal carcinoma (CRC).
- MMR-deficient CRC exhibits distinct clinicopathological features and improved survival compared to microsatellite-stable tumors.
Purpose of the Study:
- To investigate the clinicopathological characteristics and survival outcomes of colorectal cancer patients with MSI.
- To evaluate the prognostic significance of MSI in a cohort of Indian CRC patients.
Main Methods:
- Retrospective analysis of 52 colon cancer cases treated between 2017-2019.
- MSI testing performed on surgical specimens using immunohistochemistry.
- Statistical analysis of clinical data, including progression-free survival (PFS) and overall survival (OS).
Main Results:
- No significant demographic or clinicopathological differences were found between MSI-stable and MSI-unstable groups, except for a trend towards higher lymphovascular invasion in MSI-unstable cases (P=0.052).
- MSI-unstable patients demonstrated significantly longer median PFS (not reached vs. 21.3 months, P=0.049) and a trend towards longer median OS (not reached vs. 27.1 months, P=0.061) compared to MSI-stable patients.
- Overall cohort median PFS was 27.8 months.
Conclusions:
- MSI-unstable colorectal tumors are associated with improved PFS and OS.
- MSI status may serve as a favorable prognostic indicator in colorectal cancer.
- Prospective validation in larger Indian cohorts is warranted.
