title: Prognostic role of microRNA-21 in various carcinomas: a systematic review and meta-analysis.
abstract: BACKGROUND
  Recent studies have shown that microRNAs (miRNA) could play a potential role as diagnostic and prognostic biomarkers of cancers. The aim of this meta-analysis is to summarize the global predicting role of miR-21 for survival in patients with a variety of carcinomas.
  
  
  METHODS
  Eligible studies were identified and assessed for quality through multiple search strategies. Data were collected from studies comparing overall, relapse-free or cancer-specific survival (CSS) in patients with cancer having higher miR-21 expression with those having lower levels. Pooled hazard ratios (HRs) of miR-21 for survival were calculated.
  
  
  RESULTS
  A total of 17 studies dealing with various carcinomas were included for this global meta-analysis. For overall survival (OS), the pooled hazard ratio (HR) of higher miR-21 expression in cancerous tissue was 1·69 (95% CI: 1·33-2·16, P < 0·001), which could significantly predict poorer survival in general carcinomas. For relapse-free or CSS, elevated miR-21 was also a significant predictor, with a pooled HR of 1·48 (95% CI: 1·03-2·11, P = 0·033). Importantly, subgroup analysis suggested that higher expression of miR-21 correlated with worse OS in head and neck squamous cell carcinoma (HNSCC) (HR 1·46, 95% CI: 1·13-1·87, P = 0·004) and carcinomas in digestion system (HR 1·56, 95% CI: 1·08-2·26, P = 0·018).
  
  
  CONCLUSIONS
  Our findings suggest that miR-21 detection has a prognostic value in patients with cancer, especially in HNSCC and digestion system cancers.
authors.affiliation: Institutes for Advanced Interdisciplinary Research, East China Normal University, Shanghai, China.
authors.forename: Xiaonan
authors.initials: X
authors.lastname: Fu
authors.forename: Yijie
authors.initials: Y
authors.lastname: Han
authors.forename: Ying
authors.initials: Y
authors.lastname: Wu
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Zhu
authors.forename: Xin
authors.initials: X
authors.lastname: Lu
authors.forename: Feng
authors.initials: F
authors.lastname: Mao
authors.forename: Xuejing
authors.initials: X
authors.lastname: Wang
authors.forename: Xuelian
authors.initials: X
authors.lastname: He
authors.forename: Yuhang
authors.initials: Y
authors.lastname: Zhao
authors.forename: Yulan
authors.initials: Y
authors.lastname: Zhao
mesh_terms: D014408:Biomarkers, Tumor / Q000235:genetics*; D002294:Carcinoma, Squamous Cell / Q000235:genetics* / Q000401:mortality; D018572:Disease-Free Survival; D015972:Gene Expression Regulation, Neoplastic / Q000502:physiology*; D006258:Head and Neck Neoplasms / Q000235:genetics* / Q000401:mortality; D006801:Humans; D035683:MicroRNAs / Q000235:genetics*; D011237:Predictive Value of Tests; D011379:Prognosis; D013274:Stomach Neoplasms / Q000235:genetics* / Q000401:mortality; D015996:Survival Rate
chemical_list: D014408:Biomarkers, Tumor; C524940:MIRN21 microRNA, human; D035683:MicroRNAs