title: KRASMutation Test in Korean Patients with Colorectal Carcinomas: A Methodological Comparison between Sanger Sequencing and a Real-Time PCR-Based Assay.
abstract: BACKGROUND
  Mutations in theKRASgene have been identified in approximately 50% of colorectal cancers (CRCs).KRASmutations are well established biomarkers in anti-epidermal growth factor receptor therapy. Therefore, assessment ofKRASmutations is needed in CRC patients to ensure appropriate treatment.
  
  
  METHODS
  We compared the analytical performance of the cobas test to Sanger sequencing in 264 CRC cases. In addition, discordant specimens were evaluated by 454 pyrosequencing.
  
  
  RESULTS
  KRASmutations for codons 12/13 were detected in 43.2% of cases (114/264) by Sanger sequencing. Of 257 evaluable specimens for comparison,KRASmutations were detected in 112 cases (43.6%) by Sanger sequencing and 118 cases (45.9%) by the cobas test. Concordance between the cobas test and Sanger sequencing for each lot was 93.8% positive percent agreement (PPA) and 91.0% negative percent agreement (NPA) for codons 12/13. Results from the cobas test and Sanger sequencing were discordant for 20 cases (7.8%). Twenty discrepant cases were subsequently subjected to 454 pyrosequencing. After comprehensive analysis of the results from combined Sanger sequencing-454 pyrosequencing and the cobas test, PPA was 97.5% and NPA was 100%.
  
  
  CONCLUSIONS
  The cobas test is an accurate and sensitive test for detectingKRAS-activating mutations and has analytical power equivalent to Sanger sequencing. Prescreening using the cobas test with subsequent application of Sanger sequencing is the best strategy for routine detection ofKRASmutations in CRC.
authors.affiliation: Departments of Hospital Pathology, College of Medicine, The Catholic University of Korea, Seoul, Korea.
authors.forename: Sung Hak
authors.initials: SH
authors.lastname: Lee
authors.affiliation: Departments of Hospital Pathology, College of Medicine, The Catholic University of Korea, Seoul, Korea.
authors.forename: Arthur Minwoo
authors.initials: AM
authors.lastname: Chung
authors.affiliation: Departments of Hospital Pathology, College of Medicine, The Catholic University of Korea, Seoul, Korea.
authors.forename: Ahwon
authors.initials: A
authors.lastname: Lee
authors.affiliation: Departments of Hospital Pathology, College of Medicine, The Catholic University of Korea, Seoul, Korea.
authors.forename: Woo Jin
authors.initials: WJ
authors.lastname: Oh
authors.affiliation: Departments of Hospital Pathology, College of Medicine, The Catholic University of Korea, Seoul, Korea.
authors.forename: Yeong Jin
authors.initials: YJ
authors.lastname: Choi
authors.affiliation: Departments of Hospital Pathology, College of Medicine, The Catholic University of Korea, Seoul, Korea.
authors.forename: Youn-Soo
authors.initials: YS
authors.lastname: Lee
authors.affiliation: Departments of Hospital Pathology, College of Medicine, The Catholic University of Korea, Seoul, Korea.
authors.forename: Eun Sun
authors.initials: ES
authors.lastname: Jung
keywords: 454 pyrosequencing; Cobas test; KRAS mutation test; Sanger sequencing