Prognostic role of KRAS and BRAF in stage II and III resected colon cancer: results of the translational study on the PETACC-3, EORTC 40993, SAKK 60-00 trial

J Clin Oncol. 2010 Jan 20;28(3):466-74. doi: 10.1200/JCO.2009.23.3452. Epub 2009 Dec 14.

Abstract

Purpose: Mutations within the KRAS proto-oncogene have predictive value but are of uncertain prognostic value in the treatment of advanced colorectal cancer. We took advantage of PETACC-3, an adjuvant trial with 3,278 patients with stage II to III colon cancer, to evaluate the prognostic value of KRAS and BRAF tumor mutation status in this setting.

Patients and methods: Formalin-fixed paraffin-embedded tissue blocks (n = 1,564) were prospectively collected and DNA was extracted from tissue sections from 1,404 cases. Planned analysis of KRAS exon 2 and BRAF exon 15 mutations was performed by allele-specific real-time polymerase chain reaction. Survival analyses were based on univariate and multivariate proportional hazard regression models.

Results: KRAS and BRAF tumor mutation rates were 37.0% and 7.9%, respectively, and were not significantly different according to tumor stage. In a multivariate analysis containing stage, tumor site, nodal status, sex, age, grade, and microsatellite instability (MSI) status, KRAS mutation was associated with grade (P = .0016), while BRAF mutation was significantly associated with female sex (P = .017), and highly significantly associated with right-sided tumors, older age, high grade, and MSI-high tumors (all P < 10(-4)). In univariate and multivariate analysis, KRAS mutations did not have a major prognostic value regarding relapse-free survival (RFS) or overall survival (OS). BRAF mutation was not prognostic for RFS, but was for OS, particularly in patients with MSI-low (MSI-L) and stable (MSI-S) tumors (hazard ratio, 2.2; 95% CI, 1.4 to 3.4; P = .0003).

Conclusion: In stage II-III colon cancer, the KRAS mutation status does not have major prognostic value. BRAF is prognostic for OS in MS-L/S tumors.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenocarcinoma / diagnosis
  • Adenocarcinoma / genetics*
  • Adenocarcinoma / pathology
  • Adolescent
  • Adult
  • Aged
  • Colonic Neoplasms / diagnosis
  • Colonic Neoplasms / genetics*
  • Colonic Neoplasms / pathology
  • Female
  • Humans
  • Male
  • Middle Aged
  • Mutation
  • Prognosis
  • Prospective Studies
  • Proto-Oncogene Proteins / genetics*
  • Proto-Oncogene Proteins B-raf / genetics*
  • Proto-Oncogene Proteins p21(ras)
  • Young Adult
  • ras Proteins / genetics*

Substances

  • KRAS protein, human
  • Proto-Oncogene Proteins
  • BRAF protein, human
  • Proto-Oncogene Proteins B-raf
  • Proto-Oncogene Proteins p21(ras)
  • ras Proteins