Prognostic and Predictive Values of Mismatch Repair Deficiency in Non-Metastatic Colorectal Cancer

Simple Summary A subset of colorectal cancers (CRCs) displays deficient DNA mismatch repair (dMMR) that leads to microsatellite instability (MSI). These tumors have distinct clinicopathological features and have been associated with a more favorable prognosis. Knowledge of mismatch repair (MMR) status has important implications for disease diagnosis, surgical intervention, and adjuvant treatment decisions. Colorectal cancer (CRC) is the third most commonly diagnosed cancer worldwide. Universal MMR/MSI testing is standard of care for all patients with newly diagnosed CRC based on multi-society guidelines in the United States. Such testing is intended to identify patients with Lynch Syndrome due to a germline mutation in an MMR gene, but also detects those with sporadic dMMR/MSI-high CRCs. The prognostic utility of MMR/MSI status in non-metastatic colorectal cancer has been studied extensively, yet more limited data are available for its predictive utility. Results have not been entirely consistent due to potential stage-related differences and limited numbers of dMMR/MSI-H patients included in the studies. In this review, we summarize the current evidence for the prognostic and predictive value of dMMR/MSI-H in non-metastatic CRC, and discuss the use of this biomarker for patient management and treatment decisions in clinical practice.

Automated summary

dMMR/MSI-H in non-metastatic CRC has important prognostic and predictive value, guiding patient management and treatment decisions in clinical practice.