title: Tissue microRNA-21 expression predicted recurrence and poor survival in patients with colorectal cancer - a meta-analysis.
abstract: OBJECTIVE
  MicroRNA-21 (miR-21) has been shown to play an important role in cancer prognosis. We performed a meta-analysis to evaluate the prognostic effect of miR-21 from tissues and serum on survival of the patients with colorectal cancer (CRC).
  
  
  METHODS
  Relevant studies were identified by searching PubMed, Embase, and Cochrane Library. Pooled hazard ratios (HRs) with 95% confidence intervals (CIs) of total and subgroup analyses, for overall survival (OS) and disease-free survival (DFS), were calculated to investigate the association between miR-21 expression and CRC prognosis.
  
  
  RESULTS
  Our analysis included eleven studies (3,669 subjects). In addition, four studies explored the association between miR-21 and DFS, and ten studies focused on the prognostic value of miR-21 for OS. Our results indicated that increased miR-21 expression of tissues predicted both poor DFS and OS in patients with CRC (DFS: HR =1.59, 95% CI =1.20-2.10; OS: HR =1.53, 95% CI =1.23-1.90). Consistent results were observed among colon cancer and quantitative real-time polymerase chain reaction subgroups.
  
  
  CONCLUSIONS
  Meta-analysis indicated that miR-21 predicted recurrence and poor survival in patients with CRC. miR-21 may be more suitable to predict cancer prognosis in colon cancer patients.
authors.affiliation: Department of Clinical Epidemiology and Biostatistics, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, People's Republic of China.
authors.forename: Zexin
authors.initials: Z
authors.lastname: Chen
authors.affiliation: Department of Epidemiology & Health Statistics, School of Public Health, School of Medicine, Zhejiang University, Hangzhou, People's Republic of China.
authors.forename: Hui
authors.initials: H
authors.lastname: Liu
authors.affiliation: Department of Epidemiology & Health Statistics, School of Public Health, School of Medicine, Zhejiang University, Hangzhou, People's Republic of China.
authors.forename: Wen
authors.initials: W
authors.lastname: Jin
authors.affiliation: Department of Epidemiology & Health Statistics, School of Public Health, School of Medicine, Zhejiang University, Hangzhou, People's Republic of China.
authors.forename: Zheyuan
authors.initials: Z
authors.lastname: Ding
authors.affiliation: Department of Epidemiology & Health Statistics, School of Public Health, School of Medicine, Zhejiang University, Hangzhou, People's Republic of China.
authors.forename: Shuangshuang
authors.initials: S
authors.lastname: Zheng
authors.affiliation: Department of Epidemiology & Health Statistics, School of Public Health, School of Medicine, Zhejiang University, Hangzhou, People's Republic of China.
authors.forename: Yunxian
authors.initials: Y
authors.lastname: Yu
keywords: colorectal cancer; miR-21; prognostic value