title: Tubal ligation and the risk of ovarian cancer: review and meta-analysis.
abstract: BACKGROUND
  The reduction of ovarian cancer (OC) risk in women with a history of tubal ligation (TL) has been reported repeatedly, mostly on small populations. We have aimed to provide a critical overview of the studies available to date and to conduct a meta-analysis.
  
  
  METHODS
  There were 40 relevant studies identified. The studies were divided into two groups for strict and extended meta-analysis, respectively. Subgroup analysis was performed for age, time dependency since TL, histological types of OC and BReast CAncer (BRCA) mutation.
  
  
  RESULTS
  Meta-analysis of 13 strictly selected studies showed a reduced risk of epithelial OC by 34%. The protective effect of TL was confirmed even in a subgroup of women 10-14 years after the procedure. The risk reduction was confirmed for the endometrioid (RR = 0.40) and serous (RR = 0.73) cancers but not for mucinous.
  
  
  CONCLUSIONS
  The review of relevant articles, as well as the meta-analysis of selected studies, yields consistent data on a significant reduction of OC risk in women who had undergone TL. The results of this meta-analysis should provide an impulse for further research on the etiology of ovarian epithelial cancers, focusing particularly on the importance of retrograde transport of endometrial cells.
authors.affiliation: Oncogynecological Centre, Department of Obstetrics and Gynecology, General Teaching Hospital, First Medical School, Charles University, Prague, Czech Republic. david.cibula@iol.cz
authors.forename: D
authors.initials: D
authors.lastname: Cibula
authors.forename: M
authors.initials: M
authors.lastname: Widschwendter
authors.forename: O
authors.initials: O
authors.lastname: Májek
authors.forename: L
authors.initials: L
authors.lastname: Dusek
mesh_terms: D000367:Age Factors; D019313:BRCA1 Protein / Q000235:genetics; D024682:BRCA2 Protein / Q000235:genetics; D005260:Female; D006801:Humans; D010051:Ovarian Neoplasms / Q000453:epidemiology* / Q000235:genetics / Q000517:prevention & control; D011446:Prospective Studies; D012189:Retrospective Studies; D012307:Risk Factors; D013246:Sterilization, Tubal; D013997:Time Factors
chemical_list: D019313:BRCA1 Protein; C492913:BRCA1 protein, human; D024682:BRCA2 Protein; C551750:BRCA2 protein, human