title: Clinical relevance of cell-free DNA in gastrointestinal tract malignancy.
abstract: BACKGROUND
  Cell-free DNA (cfDNA) extracted from blood has become a clinically feasible biomarker in various types of cancer. However, the clinical significance of cfDNA in gastrointestinal (GI) tract cancer among Asian populations requires further investigation.
  
  
  RESULTS
  The median cfDNA copy number was highest in esophageal cancer, followed by colorectal cancer and gastric cancer, which were all significantly higher than those of healthy individuals. The cfDNA levels were higher in GI tract cancer, followed by those in carcinoma in situ and then healthy individuals (P = 0.019). During the postoperative surveillance, the cfDNA level tended to be more sensitive than the carcinoembryonic antigen level in predicting recurrence. For recurrent gastric cancer, a persistently high cfDNA level and an increasing trend was observed after surgery. For stage IV colorectal cancer, dynamic changes in the cfDNA level were correlated with the responses to chemotherapy and surgery.
  
  
  METHODS
  Blood samples were collected from 95 healthy individuals and from 855 patients diagnosed with GI tract malignancy, including 98 with esophageal cancer, 428 with stomach cancer, 329 with colorectal cancer and 30 with carcinoma in situ. The copy numbers of extracted cfDNA were analyzed and compared among the different types of GI cancers.
  
  
  CONCLUSIONS
  The cfDNA level can serve as a feasible biomarker for detecting tumors in GI tract cancer. The cfDNA level may play a role in predicting tumor responses to chemotherapy and surgery in colorectal cancer; tumor recurrence should be considered in gastric cancer with a persistently high cfDNA level after surgery.
authors.affiliation: Division of Colon and Rectal Surgery, Department of Surgery, Taipei Veterans General Hospital, Taipei, Taiwan.|Department of Surgery, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Yuan-Tzu
authors.initials: YT
authors.lastname: Lan
authors.affiliation: Division of Medical Oncology, Department of Oncology, Taipei Veterans General Hospital, Taipei, Taiwan.|School of Medicine, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Ming-Huang
authors.initials: MH
authors.lastname: Chen
authors.affiliation: Department of Surgery, National Yang-Ming University, Taipei, Taiwan.|Division of General Surgery, Department of Surgery, Taipei Veterans General Hospital, Taipei, Taiwan.
authors.forename: Wen-Liang
authors.initials: WL
authors.lastname: Fang
authors.affiliation: Division of Thoracic Surgery, Department of Surgery, Taipei Veterans General Hospital, Taipei, Taiwan.|School of Medicine, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Chih-Cheng
authors.initials: CC
authors.lastname: Hsieh
authors.affiliation: Genome Research Center, National Yang-Ming University, Taipei City, Taiwan.
authors.forename: Chien-Hsing
authors.initials: CH
authors.lastname: Lin
authors.affiliation: Division of General Surgery, Department of Surgery, Taipei Veterans General Hospital, Taipei, Taiwan.
authors.forename: Fang-Yu
authors.initials: FY
authors.lastname: Jhang
authors.affiliation: Division of Colon and Rectal Surgery, Department of Surgery, Taipei Veterans General Hospital, Taipei, Taiwan.|Department of Surgery, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Shung-Haur
authors.initials: SH
authors.lastname: Yang
authors.affiliation: Division of Colon and Rectal Surgery, Department of Surgery, Taipei Veterans General Hospital, Taipei, Taiwan.|Department of Surgery, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Jen-Kou
authors.initials: JK
authors.lastname: Lin
authors.affiliation: Division of Colon and Rectal Surgery, Department of Surgery, Taipei Veterans General Hospital, Taipei, Taiwan.|Department of Surgery, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Wei-Shone
authors.initials: WS
authors.lastname: Chen
authors.affiliation: Division of Colon and Rectal Surgery, Department of Surgery, Taipei Veterans General Hospital, Taipei, Taiwan.|Department of Surgery, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Jeng-Kai
authors.initials: JK
authors.lastname: Jiang
authors.affiliation: School of Medicine, National Yang-Ming University, Taipei, Taiwan.|Department of Clinical Pathology, Yang-Ming Branch, Taipei City Hospital, Taipei, Taiwan.
authors.forename: Pei-Ching
authors.initials: PC
authors.lastname: Lin
authors.affiliation: Division of Colon and Rectal Surgery, Department of Surgery, Taipei Veterans General Hospital, Taipei, Taiwan.|Department of Surgery, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Shih-Ching
authors.initials: SC
authors.lastname: Chang
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor; D016022:Case-Control Studies; D000073888:Cell-Free Nucleic Acids; D004273:DNA, Neoplasm; D005260:Female; D005770:Gastrointestinal Neoplasms / Q000175:diagnosis* / Q000235:genetics* / Q000628:therapy; D018628:Gene Dosage; D006801:Humans; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local; D009367:Neoplasm Staging; D009928:Organ Specificity; D012372:ROC Curve
chemical_list: D014408:Biomarkers, Tumor; D000073888:Cell-Free Nucleic Acids; D004273:DNA, Neoplasm
keywords: GI tract cancer; biomarker; carcinoembryonic antigen; cfDNA; response