Clinical validation of the detection of KRAS and BRAF mutations from circulating tumor DNA

Nat Med. 2014 Apr;20(4):430-5. doi: 10.1038/nm.3511. Epub 2014 Mar 23.


Assessment of KRAS status is mandatory in patients with metastatic colorectal cancer (mCRC) before applying targeted therapy. We describe here a blinded prospective study to compare KRAS and BRAF mutation status data obtained from the analysis of tumor tissue by routine gold-standard methods and of plasma DNA using a quantitative PCR-based method specifically designed to analyze circulating cell-free DNA (cfDNA). The mutation status was determined by both methods from 106 patient samples. cfDNA analysis showed 100% specificity and sensitivity for the BRAF V600E mutation. For the seven tested KRAS point mutations, the method exhibited 98% specificity and 92% sensitivity with a concordance value of 96%. Mutation load, expressed as the proportion of mutant alleles in cfDNA, was highly variable (0.5-64.1%, median 10.5%) among mutated samples. CfDNA was detected in 100% of patients with mCRC. This study shows that liquid biopsy through cfDNA analysis could advantageously replace tumor-section analysis and expand the scope of personalized medicine for patients with cancer.

Publication types

  • Research Support, Non-U.S. Gov't
  • Validation Study

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Case-Control Studies
  • Cohort Studies
  • Colorectal Neoplasms / diagnosis*
  • Colorectal Neoplasms / genetics
  • DNA, Neoplasm / analysis*
  • Female
  • Humans
  • Male
  • Middle Aged
  • Neoplasm Metastasis
  • Point Mutation*
  • Prospective Studies
  • Proto-Oncogene Proteins / genetics*
  • Proto-Oncogene Proteins B-raf / genetics*
  • Proto-Oncogene Proteins p21(ras)
  • Reverse Transcriptase Polymerase Chain Reaction
  • Sensitivity and Specificity
  • Sequence Analysis, DNA
  • Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
  • ras Proteins / genetics*


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