Exploring the Prognostic Role of Microsatellite Instability in Patients With Stage II Colorectal Cancer: A Systematic Review and Meta-Analysis

Many studies have disclosed the prognostic effect of microsatellite instability (MSI) and/or loss of mismatch repair proteins in colorectal cancer. Nevertheless, little evidence supports their role in decision-making of adjuvant therapy for the stage II. This systematic review evaluated the prognostic and/or predictive role of MSI status in patients with stage II colorectal cancer. Only 2 articles fulfilled the eligibility criteria, suggesting a prognostic role of MSI on disease-free survival but not supporting the hypothesis of a predictive effect. Background: Many studies have disclosed the prognostic effect of microsatellite instability (MSI) and/or loss of mismatch repair proteins in colorectal cancer. Nevertheless, little evidence supports their role in the decision-making of adjuvant therapy for patients with stage II disease. Materials and Methods: The aim of this systematic review was to evaluate the prognostic and/or predictive role of MSI status in patients with stage II colorectal cancer on disease-free survival and overall survival. MEDLINE, EMBASE, and Cochrane libraries were searched to identify eligible studies. Results: Only 2 of 389 articles identified fulfilled the eligibility criteria. In both treated and untreated patients, high-level MSI improved disease-free survival compared with low-level MSI, suggesting a prognostic role but not supporting the hypothesis of a predictive effect of MSI. Conclusions: Further studies are needed to explore the predictive role of MSI/mismatch repair proteins, because available data do not allow definitive conclusions. (C) 2016 Elsevier Inc. All rights reserved.