title: KRAS mutation analysis: a comparison between primary tumours and matched liver metastases in 305 colorectal cancer patients.
abstract: BACKGROUND
  KRAS mutation is a negative predictive factor for treatment with anti-epidermal growth factor receptor antibody in metastatic colorectal cancer (CRC). KRAS mutation analysis is usually performed on primary tumour tissue because metastatic tissue is often not available. However, controversial data are available on the concordance of test results between primary tumours and corresponding metastases. We assessed the concordance of KRAS mutation status in a study of 305 primary colorectal tumours and their corresponding liver metastases.
  
  
  METHODS
  Patients with histologically confirmed CRC who underwent surgical resection of the primary tumour and biopsy or surgical resection of the corresponding liver metastasis were included. KRAS mutation analysis was performed for codons 12 and 13.
  
  
  RESULTS
  KRAS mutation was detected in 108 out of 305 primary tumours (35.4%). In 11 cases (3.6%), we found a discordance between primary tumour and metastasis: 5 primary tumours had a KRAS mutation with a wild-type metastasis, 1 primary tumour was wild type with a KRAS mutation in the metastasis, and in 5 cases the primary tumour and the metastasis had a different KRAS mutation.
  
  
  CONCLUSIONS
  We observed a high concordance of KRAS mutation status of 96.4% (95% CI 93.6-98.2%) between primary colorectal tumours and their corresponding liver metastases. In only six patients (2.0%; 95% CI 0.7-4.2%), the discordance was clinically relevant. In this largest and most homogenous study to date, we conclude that both primary tumours and liver metastases can be used for KRAS mutation analysis.
authors.affiliation: Department of Medical Oncology, Radboud University Nijmegen Medical Centre, PO Box 9101, Nijmegen, HB 6500, The Netherlands.
authors.forename: N
authors.initials: N
authors.lastname: Knijn
authors.forename: L J M
authors.initials: LJ
authors.lastname: Mekenkamp
authors.forename: M
authors.initials: M
authors.lastname: Klomp
authors.forename: M E
authors.initials: ME
authors.lastname: Vink-Börger
authors.forename: J
authors.initials: J
authors.lastname: Tol
authors.forename: S
authors.initials: S
authors.lastname: Teerenstra
authors.forename: J W R
authors.initials: JW
authors.lastname: Meijer
authors.forename: M
authors.initials: M
authors.lastname: Tebar
authors.forename: S
authors.initials: S
authors.lastname: Riemersma
authors.forename: J H J M
authors.initials: JH
authors.lastname: van Krieken
authors.forename: C J A
authors.initials: CJ
authors.lastname: Punt
authors.forename: I D
authors.initials: ID
authors.lastname: Nagtegaal
mesh_terms: D000368:Aged; D002277:Carcinoma / Q000235:genetics* / Q000473:pathology; D015331:Cohort Studies; D015179:Colorectal Neoplasms / Q000235:genetics* / Q000473:pathology; D004252:DNA Mutational Analysis / Q000379:methods*; D005260:Female; D011905:Genes, ras; D006801:Humans; D008113:Liver Neoplasms / Q000235:genetics* / Q000556:secondary; D008297:Male; D016555:Matched-Pair Analysis; D008875:Middle Aged; D008954:Models, Biological; D015337:Multicenter Studies as Topic; D009154:Mutation