The Association between Endometriosis, Tubal Ligation, Hysterectomy and Epithelial Ovarian Cancer: Meta-Analyses

To investigate the association between endometriosis, tubal ligation, hysterectomy and epithelial ovarian cancer. Relevant published literatures were searched in PubMed, ProQuest, Web of Science and Medline databases during 1995-2016. Heterogeneity was evaluated by I-2 statistic. Publication bias was tested by funnel plot and Egger's test. Odds ratio and 95% CI were used to assess the association strength. The statistical analyses in this study were accomplished by STATA software package. A total of 40,609 cases of epithelial ovarian cancer and 368,452 controls in 38 publications were included. The result suggested that endometriosis was associated with an increased risk of epithelial ovarian cancer (OR = 1.42, 95% CI = 1.28-1.57), tubal ligation was associated with a decreased risk of epithelial ovarian cancer (OR = 0.70, 95% CI = 0.60-0.81), while hysterectomy show no relationship with epithelial ovarian cancer (OR = 0.97, 95% CI = 0.81-1.14). A stratified analysis showed there were associations between endometriosis and the increased risk of epithelial ovarian cancer for studies conducted in USA and Europe. Meanwhile, there were associations between tubal ligation and the decreased risk of epithelial ovarian cancer for studies conducted in USA, Asia, Europe and Australia. The result indicated that endometriosis was a risk factor of epithelial ovarian cancer whereas tubal ligation was a protective risk factor of epithelial ovarian cancer, hysterectomy may have no relationship with epithelial ovarian cancer.