Prognostic and predictive value of microsatellite instability status among patients with colorectal cancer.

Objectives: Compare overall survival (OS) between microsatellite instability (MSI) high and MSI-stable and analyze the effect of chemotherapy on OS. Methods: National cancer database was queried for patients diagnosed with colorectal adenocarcinoma between 2010 and 2016. We evaluated the OS and the chemotherapy effect using Kaplan-Meier estimates and multivariate Cox regression analyses. Results: Total of 30,436 stage II patients and 30,302 stage III patients were included. In stage II with high-risk features and MSI-high, patients who received chemotherapy had better OS compared to patients who didn't receive chemotherapy. The same was found in stage II with no high-risk features and MSI-high group. Conclusion: Stage II colorectal cancer patients with high-risk features and MSI-high who received chemotherapy have better OS compared to patients who didn't receive chemotherapy.