title: KRAS discordance between primary and recurrent tumors after radical resection of colorectal cancers.
abstract: BACKGROUND
  Although KRAS shows high concordance between primary and metastatic colorectal cancers, recent studies have reported discordance and intra-tumoral heterogeneity. To evaluate KRAS concordance between primary colorectal cancers and recurrent tumors after radical resection, we performed this study.
  
  
  METHODS
  Between January 2007 and August 2013, among patients underwent radical resection for primary colorectal cancers and tissue sampling of recurred tumors including resection or biopsy, 74 patients whose both primary and recurred tumor tissues were available for KRAS analysis were enrolled. The clinical and pathologic data were retrospectively revised and KRAS analyses were performed.
  
  
  RESULTS
  The patients with initial M1 stage showed significantly higher KRAS discordance rate (54.5%). The KRAS concordance rate was 79.7% (n = 59). Forty-two patients (56.8%) showed the wild-to-wild type and 17 (22.9%) showed the mutant-to-mutant type. The discordance rate was 20.3% (n = 15). Eight patients (10.8%) showed the wild-to-mutant type, and 7 (9.5%) showed the mutant-to-wild type. Among 15 discordance cases, intra-tumoral heterogeneity was found in 26.7% (n = 4).
  
  
  CONCLUSIONS
  There is 20.3% KRAS discordance between primary and recurrent tumors, which is higher rate than is generally known. For selection of the effective target agent, KRAS analysis of recurred tumors will be necessary, if it is available.
authors.affiliation: Department of Surgery, Chungnam National University Hospital, Daejeon, South Korea.
authors.forename: Kyung Ha
authors.initials: KH
authors.lastname: Lee
authors.affiliation: Department of Surgery, Chungnam National University Hospital, Daejeon, South Korea.
authors.forename: Jin Soo
authors.initials: JS
authors.lastname: Kim
authors.affiliation: Department of Pathology, Chungnam National University Hospital, Daejeon, South Korea.
authors.forename: Choong Sik
authors.initials: CS
authors.lastname: Lee
authors.affiliation: Department of Surgery, Chungnam National University Hospital, Daejeon, South Korea.
authors.forename: Ji Yeon
authors.initials: JY
authors.lastname: Kim
mesh_terms: D000368:Aged; D015179:Colorectal Neoplasms / Q000235:genetics* / Q000473:pathology / Q000601:surgery*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000235:genetics* / Q000473:pathology / Q000601:surgery*; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D016283:Proto-Oncogene Proteins p21(ras); D018631:ras Proteins / Q000235:genetics*
chemical_list: C117307:KRAS protein, human; D011518:Proto-Oncogene Proteins; D016283:Proto-Oncogene Proteins p21(ras); D018631:ras Proteins
keywords: KRAS protein; colorectal neoplasms; neoplasm metastasis