title: Reliability of KRAS mutation testing in metastatic colorectal cancer patients across five laboratories.
abstract: BACKGROUND
  Mutations in the KRAS gene are associated with poor response to epidermal growth factor receptor inhibitors used in the treatment of metastatic colorectal cancer. Factors influencing KRAS test results in tumor specimens include: tumor heterogeneity, sample handling, slide preparation, techniques for tumor enrichment, DNA preparation, assay design and sensitivity. We evaluated comparability and consistency of KRAS test results among five laboratories currently being used to determine KRAS mutation status of metastatic colorectal cancer specimens in a large, multi-center observational study.
  
  
  RESULTS
  Twenty formalin-fixed paraffin-embedded human colorectal cancer samples from colon resections previously tested for KRAS mutations were selected based on mutation status (6 wild type, 8 codon 12 mutations, and 6 codon 13 mutations). We found good agreement across laboratories despite differences in mutation detection methods. Eighteen of twenty samples (90%) were concordant across all five labs. Discordant results are likely not due to laboratory error, but instead to tumor heterogeneity, contamination of the tumor sample with normal tissue, or analytic factors affecting assay sensitivity.
  
  
  CONCLUSIONS
  Our results indicate commercial and academic laboratories provide reliable results for the common KRAS gene mutations at codons 12 and 13 when an adequate percentage of tumor cells is present in the sample.
authors.affiliation: Institute for Health Research Legacy Highlands, Kaiser Permanente Colorado, Denver, CO 80237-8066, USA. heather.s.feigelson@kp.org
authors.forename: Heather Spencer
authors.initials: HS
authors.lastname: Feigelson
authors.forename: Katrina A B
authors.initials: KA
authors.lastname: Goddard
authors.forename: Monique A
authors.initials: MA
authors.lastname: Johnson
authors.forename: Kellyan C
authors.initials: KC
authors.lastname: Funk
authors.forename: Alanna Kulchak
authors.initials: AK
authors.lastname: Rahm
authors.forename: Tia L
authors.initials: TL
authors.lastname: Kauffman
authors.forename: Dhananjay A
authors.initials: DA
authors.lastname: Chitale
authors.forename: Loic
authors.initials: L
authors.lastname: Le Marchand
authors.forename: C Sue
authors.initials: CS
authors.lastname: Richards
mesh_terms: D000230:Adenocarcinoma / Q000235:genetics* / Q000556:secondary; D000368:Aged; D000369:Aged, 80 and over; D002277:Carcinoma / Q000235:genetics* / Q000556:secondary; D019411:Clinical Laboratory Techniques / Q000592:standards*; D003062:Codon; D015179:Colorectal Neoplasms / Q000235:genetics* / Q000473:pathology; D004252:DNA Mutational Analysis / Q000592:standards*; D017408:Guidelines as Topic / Q000592:standards; D006801:Humans; D008875:Middle Aged; D009154:Mutation; D015588:Observer Variation; D016612:Paraffin Embedding; D011237:Predictive Value of Tests; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D016283:Proto-Oncogene Proteins p21(ras); D011786:Quality Control; D060888:Real-Time Polymerase Chain Reaction / Q000592:standards; D015203:Reproducibility of Results; D016707:Tissue Fixation; D014481:United States; D018631:ras Proteins / Q000235:genetics*
chemical_list: D003062:Codon; C117307:KRAS protein, human; D011518:Proto-Oncogene Proteins; D016283:Proto-Oncogene Proteins p21(ras); D018631:ras Proteins