title: Serum dickkopf-1 as a biomarker in screening gastrointestinal cancers: a systematic review and meta-analysis.
abstract: OBJECTIVE
  Despite advances in the early diagnosis of gastrointestinal (GI) cancers, these cancers are often being detected rather late in their course. Emerging published data on the accuracy of dickkopf-1 (DKK1) for diagnosing GI cancers are inconsistent. The purpose of this systematic review and meta-analysis was to evaluate the diagnostic value of DKK1 in the diagnosis of GI cancers.
  
  
  METHODS
  A systematic literature search of PubMed, Web of Science, Embase, Chinese National Knowledge Infrastructure, and WANFANG databases was conducted to identify the related studies published before May 1, 2015, which investigated the diagnostic value of serum DKK1 for GI cancers. The methodological quality of each study was assessed according to the Quality Assessment of Diagnostic Accuracy Studies 2 checklist. The diagnostic performance was pooled and analyzed using a bivariate model. Publication bias was evaluated with the Deeks' funnel test.
  
  
  RESULTS
  A total of 15 studies with 5,076 participants were finally identified for the meta-analysis. The pooled results of sensitivity (SEN), specificity (SPE), positive likelihood ratio, negative likelihood ratio, and diagnostic odds ratio for DKK1 test were 0.72 (95% confidence interval [CI]: 0.70-0.74), 0.90 (95% CI: 0.89-0.91), 7.72 (95% CI: 4.90-12.14), 0.29 (95% CI: 0.22-0.39), and 28.95 (95% CI: 16.25-51.65) for diagnosis of GI cancers, respectively. The area under the summary receiver-operating characteristic curve was 0.8901. The SEN of DKK1 in diagnosis of gastric cancer and pancreatic cancer may be higher than hepatocellular carcinoma, and the SPE in pancreatic cancer subgroup was lower than hepatocellular carcinoma and gastric cancer subgroups.
  
  
  CONCLUSIONS
  The currently available evidence suggests that serum DKK1 is a potential biomarker with high SEN and SPE for screening GI cancers. To better elucidate the usefulness of serum DKK1, further studies are needed.
authors.affiliation: Key Laboratory of Cell Biology, Biochip Center, Ministry of Public Health, China Medical University, Shenyang, People's Republic of China.
authors.forename: Bin
authors.initials: B
authors.lastname: Liang
authors.affiliation: Key Laboratory of Cell Biology, Biochip Center, Ministry of Public Health, China Medical University, Shenyang, People's Republic of China.
authors.forename: Liansheng
authors.initials: L
authors.lastname: Zhong
authors.affiliation: Key Laboratory of Cell Biology, Biochip Center, Ministry of Public Health, China Medical University, Shenyang, People's Republic of China.
authors.forename: Qun
authors.initials: Q
authors.lastname: He
authors.affiliation: Key Laboratory of Cell Biology, Biochip Center, Ministry of Public Health, China Medical University, Shenyang, People's Republic of China.
authors.forename: Shaocheng
authors.initials: S
authors.lastname: Wang
authors.affiliation: Key Laboratory of Cell Biology, Biochip Center, Ministry of Public Health, China Medical University, Shenyang, People's Republic of China.
authors.forename: Zhongcheng
authors.initials: Z
authors.lastname: Pan
authors.affiliation: Key Laboratory of Cell Biology, Biochip Center, Ministry of Public Health, China Medical University, Shenyang, People's Republic of China.
authors.forename: Tianjiao
authors.initials: T
authors.lastname: Wang
authors.affiliation: Key Laboratory of Cell Biology, Biochip Center, Ministry of Public Health, China Medical University, Shenyang, People's Republic of China.
authors.forename: Yujie
authors.initials: Y
authors.lastname: Zhao
keywords: accuracy; cancer screening; dickkopf-1; gastrointestinal cancer