title: Circulating DNA for detection of gastric cancer.
abstract: Gastric cancer (GC) is one of the most common malignant tumors worldwide, particularly, prevalent in China. Despite the decreasing incidence of GC in China, the 5-year survival rate is still not over 30% yet. Therefore, early diagnosis and therapeutic outcome evaluation of GC remains as the issue to be resolved in a clinical setting.
  
  
  
  Recent studies have found the presence of a certain amount of circulating DNA in the peripheral blood of patients with malignant tumor and shown that these free DNA bear tumor-specific genetic information. The circulating DNA detection includes quantitative and qualitative methods and analysis. Combined monitoring of changes in circulating DNA levels and aberrant alteration of relevant tumor genes is likely to provide comprehensive real-time information to patients.
  
  
  
  Under normal conditions, oncogene presents in the form of proto-oncogene such as K-ras, which is in non-carcinogenic status under the influence of tumor suppressor gene. When tumor suppressor gene is damaged or mutated of oncogene itself is induced for instance P53, oncogene is then activated and induces tumorigenesis. However, compared to gene mutation detection, the detection of DNA methylation is relatively more well-developed and stable.
  
  
  
  This article reviews the current status of the research on circulating DNA in the diagnosis, assessment of response to therapy and prognostic evaluation in GC. In addition, the advantage, current issue and prospect of using circulating DNA as tumor marker are also analyzed.
authors.affiliation: Department of Oncology, Huzhou Central Hospital, Huzhou, China. loveshohoo@163.com.
authors.forename: Q
authors.initials: Q
authors.lastname: Qi
authors.forename: Y-F
authors.initials: YF
authors.lastname: Pan
authors.forename: J-J
authors.initials: JJ
authors.lastname: Shen
authors.forename: X-Q
authors.initials: XQ
authors.lastname: Gu
authors.forename: S-W
authors.initials: SW
authors.lastname: Han
authors.forename: H-H
authors.initials: HH
authors.lastname: Liao
authors.forename: Y-Z
authors.initials: YZ
authors.lastname: Jiang
authors.forename: L-P
authors.initials: LP
authors.lastname: Zhong
mesh_terms: D014408:Biomarkers, Tumor; D002681:China; D019175:DNA Methylation; D004273:DNA, Neoplasm / Q000097:blood*; D006801:Humans; D011379:Prognosis; D000090063:Proto-Oncogene Mas; D013274:Stomach Neoplasms / Q000175:diagnosis* / Q000235:genetics*
chemical_list: D014408:Biomarkers, Tumor; D004273:DNA, Neoplasm; C000715470:MAS1 protein, human; D000090063:Proto-Oncogene Mas