Microsatellite instability in north Indian colorectal cancer patients and its clinicopathological correlation

Colorectal cancer (CRC) is the third most deadly and fourth most commonly diagnosed cancer in the world. Microsatellite instability (MSI) has been found associated with CRC, especially in prognostication. The present study has been carried out to find the genetic instability as demonstrated by MSI and its clinicopathological correlation in north Indian patients.

This prospective study was carried out on 103 CRC patients admitted for surgery between 2014 and 2018. MSI testing was done using 5-panel markers (BAT25, BAT26, D2S123, D5S346, and D17S250) by standard polymerase chain reaction (PCR) technique. The various clinicopathological factors were analysed to see their association with MSI status and also their effect on survival. Univariate analysis was performed by using the 2-tailed Student's t-test for continuous non-normally distributed variables, and categorical variables were compared using the chi-square test. Multivariate correlation analysis was performed by logistic regression test using SPSS version 16.0 (IBM Corporation, Armonk, NY, USA). Kaplan-Meier analysis was done to detect the patient's survival. A p-value < 0.05 was considered statistically significant.

The frequency of MSI in patient population that we studied was 41.7% (43/103). MSI tumours were significantly associated with family history (OR = 5.63, p = 0.022*, 95% CI = 1.1-28.6) and tumour-infiltrating lymphocytes (TILS) (OR = 2.60, p = 0.023*, 95% CI = 1.1-6.0). The patients surviving longer (< 5 years vs > 5 years) were found significantly associated with MSI-high (MSI-H) (OR = 3.76, p = 0.029*, 95% CI = 1.2-4.5).

Family history of cancer and presence of TILS were significantly associated with the presence of MSI-H tumours; also, patients surviving more than 5 years had more MSI-H phenotype.