title: Tubal ligation, hysterectomy and ovarian cancer: A meta-analysis.
abstract: OBJECTIVE
  The purpose of this meta-analysis was to determine the strength of the association between gynecologic surgeries, tubal ligation and hysterectomy, and ovarian cancer.
  
  
  METHODS
  We searched the PubMed, Web of Science, and Embase databases for all English-language articles dated between 1969 through March 2011 using the keywords "ovarian cancer" and "tubal ligation" or "tubal sterilization" or "hysterectomy." We identified 30 studies on tubal ligation and 24 studies on hysterectomy that provided relative risks for ovarian cancer and a p-value or 95% confidence interval (CI) to include in the meta-analysis. Summary RRs and 95% CIs were calculated using a random-effects model.
  
  
  RESULTS
  The summary RR for women with vs. without tubal ligation was 0.70 (95%CI: 0.64, 0.75). Similarly, the summary RR for women with vs. without hysterectomy was 0.74 (95%CI: 0.65, 0.84). Simple hysterectomy and hysterectomy with unilateral oophorectomy were associated with a similar decrease in risk (summery RR = 0.62, 95%CI: 0.49-0.79 and 0.60, 95%CI: 0.47-0.78, respectively). In secondary analyses, the association between tubal ligation and ovarian cancer risk was stronger for endometrioid tumors (summary RR = 0.45, 95%CI: 0.33, 0.61) compared to serous tumors.
  
  
  CONCLUSIONS
  Observational epidemiologic evidence strongly supports that tubal ligation and hysterectomy are associated with a decrease in the risk of ovarian cancer, by approximately 26-30%. Additional research is needed to determine whether the association between tubal ligation and hysterectomy on ovarian cancer risk differs by individual, surgical, and tumor characteristics.
authors.affiliation: Channing Laboratory, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA. nhmsr@channing.harvard.edu.
authors.forename: Megan S
authors.initials: MS
authors.lastname: Rice
authors.forename: Megan A
authors.initials: MA
authors.lastname: Murphy
authors.forename: Shelley S
authors.initials: SS
authors.lastname: Tworoger