title: Circulating free DNA as biomarker and source for mutation detection in metastatic colorectal cancer.
abstract: BACKGROUND
  Circulating cell-free DNA (cfDNA) in plasma has shown potential as biomarker in various cancers and could become an importance source for tumour mutation detection. The objectives of our study were to establish a normal range of cfDNA in a cohort of healthy individuals and to compare this with four cohorts of metastatic colorectal cancer (mCRC) patients. We also investigated the prognostic value of cfDNA and analysed the tumour-specific KRAS mutations in the plasma.
  
  
  METHODS
  The study was a prospective biomarker evaluation in four consecutive Phase II trials, including 229 patients with chemotherapy refractory mCRC and 100 healthy individuals. Plasma was obtained from an EDTA blood-sample, and the total number of DNA alleles and KRAS mutated alleles were assessed using an in-house ARMS-qPCR as previously described.
  
  
  RESULTS
  Median cfDNA levels were higher in mCRC compared to controls (p < 0.0001). ROC analysis revealed an AUC of 0.9486 (p<0.00001). Data showed impaired OS with increasing levels of baseline cfDNA both when categorising patients by quartiles of cfDNA and into low or high cfDNA groups based on the upper normal range of the control group (Median OS 10.2 (8.3-11.7) and 5.2 (4.6-5.9) months, respectively, HR 1.78, p = 0.0006). Multivariate analysis confirmed an independent prognostic value of cfDNA (HR 1.5 (95% CI 1.3-1.7) for each increase in the cfDNA quartile). The overall concordance of KRAS mutations in plasma and tissue was high (85%).
  
  
  CONCLUSIONS
  These data confirm the prognostic value of cfDNA measurement in plasma and utility for mutation detection with the method presented.
authors: Department of Oncology, Vejle Hospital, Vejle, Denmark.
authors: Karen Lise Garm
authors: KL
authors: Spindler
authors: Department of Biochemistry, Vejle Hospital, Vejle, Denmark.
authors: Niels
authors: N
authors: Pallisgaard
authors: Department of Biochemistry, Vejle Hospital, Vejle, Denmark.
authors: Rikke Fredslund
authors: RF
authors: Andersen
authors: Department of Biochemistry, Vejle Hospital, Vejle, Denmark.
authors: Ivan
authors: I
authors: Brandslund
authors: Department of Oncology, Vejle Hospital, Vejle, Denmark.
authors: Anders
authors: A
authors: Jakobsen
mesh_terms: D000328:Adult; D000368:Aged; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D014408:Biomarkers, Tumor / Q000097:blood / Q000235:genetics; D003106:Colon / Q000187:drug effects / Q000473:pathology; D015179:Colorectal Neoplasms / Q000097:blood / Q000188:drug therapy / Q000235:genetics* / Q000473:pathology*; D004247:DNA / Q000097:blood* / Q000235:genetics*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009154:Mutation; D009362:Neoplasm Metastasis / Q000188:drug therapy / Q000235:genetics* / Q000473:pathology; D011379:Prognosis; D011446:Prospective Studies; D016283:Proto-Oncogene Proteins p21(ras) / Q000235:genetics; D012007:Rectum / Q000187:drug effects / Q000473:pathology
chemical_list: D014408:Biomarkers, Tumor; C117307:KRAS protein, human; D004247:DNA; D016283:Proto-Oncogene Proteins p21(ras)