Microsatellite instability has a positive prognostic impact on stage II colorectal cancer after complete resection: results from a large, consecutive Norwegian series

Ann Oncol. 2013 May;24(5):1274-82. doi: 10.1093/annonc/mds614. Epub 2012 Dec 12.


Background: Microsatellite instability (MSI) was suggested as a marker for good prognosis in colorectal cancer in 1993 and a systematic review from 2005 and a meta-analysis from 2010 support the initial observation. We here assess the prognostic impact and prevalence of MSI in different stages in a consecutive, population-based series from a single hospital in Oslo, Norway.

Patients and methods: Of 1274 patients, 952 underwent major resection of which 805 were included in analyses of MSI prevalence and 613 with complete resection in analyses of outcome. Formalin-fixed tumor tissue was used for PCR-based MSI analyses.

Results: The overall prevalence of MSI was 14%, highest in females (19%) and in proximal colon cancer (29%). Five-year relapse-free survival (5-year RFS) was 67% and 55% (P = 0.030) in patients with MSI and MSS tumors, respectively, with the hazard ratio (HR) equal to 1.60 (P = 0.045) in multivariate analysis. The improved outcome was confined to stage II patients who had 5-year RFS of 74% and 56% respectively (P = 0.010), HR = 2.02 (P = 0.040). Examination of 12 or more lymph nodes was significantly associated with proximal tumor location (P < 0.001).

Conclusions: MSI has an independent positive prognostic impact on stage II colorectal cancer patients after complete resection.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Aged, 80 and over
  • Biomarkers, Tumor / genetics
  • Colorectal Neoplasms / genetics*
  • Colorectal Neoplasms / mortality
  • Colorectal Neoplasms / surgery*
  • Disease-Free Survival
  • Female
  • Humans
  • Lymph Nodes / pathology
  • Lymphatic Metastasis
  • Male
  • Microsatellite Instability*
  • Middle Aged
  • Neoplasm Recurrence, Local / genetics*
  • Neoplasm Staging
  • Norway
  • Prognosis


  • Biomarkers, Tumor