title: K-ras mutations are found in DNA extracted from the plasma of patients with colorectal cancer.
abstract: OBJECTIVE
  Circulating DNA can be isolated from the plasma of healthy subjects and from patients with cancer. The aim of this study was to detect K-ras mutations in DNA extracted from the plasma of patients with colorectal cancer.
  
  
  METHODS
  Tumor and plasma DNA were extracted from 14 patients with colorectal cancer (stages A-D), and K-ras alterations were detected using a polymerase chain reaction assay that uses sequence-specific primers to amplify mutant DNA. These results were confirmed with another polymerase chain reaction assay that creates an enzyme restriction site in the absence of a K-ras mutation followed by direct sequencing and additional cloning techniques.
  
  
  RESULTS
  Seven patients (50%) had a codon 12 K-ras mutation within their primary tumor, and identical mutations were found in the plasma DNA of 6 patients (86%). Mutant DNA was not detected in the plasma specimens of 7 patients whose tumors tested negative for K-ras alterations or in healthy control subjects. Similar results were obtained using all three molecular biological techniques.
  
  
  CONCLUSIONS
  K-ras abnormalities can be detected in circulating DNA extracted from the plasma specimens of patients with colorectal cancer. If these results are confirmed in larger studies, genetic analysis of plasma DNA may have clinical applications in the future.
authors.affiliation: Département de Biochimie et de Physiologie Végétale, Université de Genève, Switzerland.
authors.forename: P
authors.initials: P
authors.lastname: Anker
authors.forename: F
authors.initials: F
authors.lastname: Lefort
authors.forename: V
authors.initials: V
authors.lastname: Vasioukhin
authors.forename: J
authors.initials: J
authors.lastname: Lyautey
authors.forename: C
authors.initials: C
authors.lastname: Lederrey
authors.forename: X Q
authors.initials: XQ
authors.lastname: Chen
authors.forename: M
authors.initials: M
authors.lastname: Stroun
authors.forename: H E
authors.initials: HE
authors.lastname: Mulcahy
authors.forename: M J
authors.initials: MJ
authors.lastname: Farthing
mesh_terms: D000328:Adult; D000368:Aged; D001435:Bacteriophages / Q000235:genetics; D001483:Base Sequence; D003001:Cloning, Molecular; D015179:Colorectal Neoplasms / Q000097:blood / Q000235:genetics*; D004273:DNA, Neoplasm / Q000235:genetics*; D005260:Female; D011905:Genes, ras; D006801:Humans; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D009154:Mutation; D015345:Oligonucleotide Probes; D016133:Polymerase Chain Reaction / Q000379:methods; D012150:Polymorphism, Restriction Fragment Length
chemical_list: D004273:DNA, Neoplasm; D015345:Oligonucleotide Probes