title: Phytoestrogen intake and risk of ovarian cancer: a meta- analysis of 10 observational studies.
abstract: BACKGROUND
  Epidemiology studies have shown an inconclusive relationship between phytoestrogen intake and ovarian cancer risk and there have been no relevant meta-analyses directly regarding this topic. The purpose of the present meta-analysis was therefore to investigate any association between phytoestrogen intake and ovarian cancer in detail.
  
  
  METHODS
  We conducted a search of PubMed, EMBASE, EBSCO, the Cochrane Library, CNKI and Chinese Biomedical Database (up to April 2014) using common keywords for studies that focused on phytoestrogen and ovarian cancer risk. Study-specific risk estimates (RRs) were pooled using fixed effect or random-effect models.
  
  
  RESULTS
  Ten epidemiologic studies were finally included in the meta-analysis. The total results indicated higher phytoestrogen intake was associated with a reduced ovarian cancer risk (RR, 0.70; 95%CI: 0.56-0.87). The association was similar in sensitivity analysis. Meta regression analysis demonstrated sources and possibly types and regions as heterogeneous factors. Subgroup analysis of types, sources and regions showed that isoflavones (RR: 0.63; 95%CI: 0.46, 0.86), soy foods (RR: 0.51; 95%CI: 0.39, 0.68) and an Asian diet (RR: 0.48; 95%CI: 0.37, 0.63) intake could reduce the incidence of ovarian cancer.
  
  
  CONCLUSIONS
  Our findings show possible protection by phytoestrogens against ovarian cancer. We emphasize specific phytoestrogens from soy foods, but not all could reduce the risk. The habit of plentiful phytoestrogen intake by Asians is worthy to recommendation. However, we still need additional larger well designed observational studies to fully characterize underlying associations.
authors.affiliation: The Reproductive Medicine Center, Zhongnan Hospital of Wuhan University, Wuhan, China E-mail : zhangyuanzhen@vip.sina.com.
authors.forename: Xin-Lan
authors.initials: XL
authors.lastname: Qu
authors.forename: Yuan
authors.initials: Y
authors.lastname: Fang
authors.forename: Ming
authors.initials: M
authors.lastname: Zhang
authors.forename: Yuan-Zhen
authors.initials: YZ
authors.lastname: Zhang
mesh_terms: D002681:China / Q000453:epidemiology; D004032:Diet; D005260:Female; D006801:Humans; D015994:Incidence; D064887:Observational Studies as Topic; D010051:Ovarian Neoplasms / Q000453:epidemiology / Q000517:prevention & control*; D048789:Phytoestrogens / Q000008:administration & dosage*; D011379:Prognosis; D012307:Risk Factors
chemical_list: D048789:Phytoestrogens