Prognostic and predictive roles of high-degree microsatellite instability in colon cancer: A National Cancer Institute-national surgical adjuvant breast and bowel project collaborative study

Abstract

Purpose: The role of high-degree microsatellite instability (MSI-H) as a marker to predict benefit from adjuvant chemotherapy remains unclear. Patients and Methods: To help define its impact, we conducted an analysis of National Surgical Adjuvant Breast and Bowel Project (NSABP) patients who were randomly assigned to a surgery-alone group (untreated cohort) and patients assigned to an adjuvant fluorouracil (FU) -treated group (treated cohort). MSI-H and other potential markers were assessed (TGF-BRII, p53, thymidylate synthase, and Ki67). Results: In all, 98 (18.1%) of 542 patients exhibited MSI-H, and there was a strong inverse relationship between MSI-H and mutant p53 status (P