title: Microsatellite instability in the management of colorectal cancer.
abstract: Microsatellite instability (MSI) is a form of genetic instability caused by alterations in the DNA mismatch repair system. Approximately 15% of colorectal cancers display MSI due to a germline mutation in one of the mismatch repair genes (MLH1, MSH2, MSH6 and PMS2) or to epigenetic silencing of MLH1. Colorectal cancers with MSI have distinctive features, including a tendency to arise in the proximal colon, poor differentiation, lymphocytic infiltration and mucinous or signet-ring histology. Patients with MSI tumors appear to have a better prognosis than those with microsatellite stable tumors, but curiously the responses to 5-fluorouracil-based chemotherapy regimens are poorer with MSI tumors. Preliminary data suggest possible advantages of irinotecan-based regimens, but these findings need validation in well-designed clinical trials.
authors.affiliation: Gastrointestinal Unit, Massachusetts General Hospital, 50 Blossom Street, Boston, MA 02114, USA.
authors.forename: Maria S
authors.initials: MS
authors.lastname: Pino
authors.forename: Daniel C
authors.initials: DC
authors.lastname: Chung
mesh_terms: D000970:Antineoplastic Agents / Q000627:therapeutic use*; D015179:Colorectal Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology; D003123:Colorectal Neoplasms, Hereditary Nonpolyposis / Q000188:drug therapy / Q000235:genetics; D053843:DNA Mismatch Repair; D015972:Gene Expression Regulation, Neoplastic; D005820:Genetic Testing; D005838:Genotype; D006801:Humans; D007150:Immunohistochemistry; D053842:Microsatellite Instability; D018579:Patient Selection; D010641:Phenotype; D057285:Precision Medicine; D016896:Treatment Outcome
chemical_list: D000970:Antineoplastic Agents