title: Microsatellite instability is a favorable prognostic indicator in patients with colorectal cancer receiving chemotherapy.
abstract: OBJECTIVE
  Adjuvant 5-fluorouracil (5-FU)-based chemotherapy is standard treatment for stage C colorectal cancer (CRC). Approximately 12% of CRCs are characterized by microsatellite instability (MSI), a hallmark of a DNA mismatch repair defect. We investigated the safety of adjuvant 5-FU-based chemotherapy for MSI(+) CRC and compared the prognosis of MSI(+) and MSI(-) CRC patients receiving adjuvant therapy.
  
  
  METHODS
  Previously, a prospective series consisting of 1044 consecutive CRCs has been collected and the MSI status of each sample determined. Patients with stage C cancer who had received adjuvant chemotherapy (n = 95) were followed up for 7-63 months (median, 31 months) after surgery.
  
  
  RESULTS
  No unexpected or serious adverse effects were observed when 5-FU-based chemotherapy was used as adjuvant treatment for MSI(+) CRC. Three- year recurrence-free survival was 90% and 43% in the MSI(+) (n = 11) and MSI(-) (n = 84) groups, respectively (P = 0.020).
  
  
  CONCLUSIONS
  Adjuvant 5-FU-based chemotherapy is feasible for both MSI(+) and MSI(-) CRCs, and patients with MSI(+) CRC who receive adjuvant therapy have an excellent prognosis.
authors.affiliation: Department of Medical Genetics, Haartman Institute, University of Helsinki, Helsinki, Finland. akseli.hemminki@ccc.uab.edu
authors.forename: A
authors.initials: A
authors.lastname: Hemminki
authors.forename: J P
authors.initials: JP
authors.lastname: Mecklin
authors.forename: H
authors.initials: H
authors.lastname: Järvinen
authors.forename: L A
authors.initials: LA
authors.lastname: Aaltonen
authors.forename: H
authors.initials: H
authors.lastname: Joensuu
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D020137:Base Pair Mismatch; D017024:Chemotherapy, Adjuvant; D003110:Colonic Neoplasms / Q000188:drug therapy / Q000235:genetics / Q000401:mortality / Q000473:pathology / Q000601:surgery; D015179:Colorectal Neoplasms / Q000188:drug therapy* / Q000235:genetics* / Q000401:mortality / Q000473:pathology / Q000601:surgery; D004260:DNA Repair; D018572:Disease-Free Survival; D005260:Female; D005472:Fluorouracil / Q000627:therapeutic use*; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D018895:Microsatellite Repeats; D008875:Middle Aged; D009367:Neoplasm Staging; D011379:Prognosis; D012004:Rectal Neoplasms / Q000188:drug therapy / Q000235:genetics / Q000401:mortality / Q000473:pathology / Q000601:surgery; D015996:Survival Rate
chemical_list: D005472:Fluorouracil