2.3 Data extraction
Information was collected for each study including the following aspects: (1) name of the first author; (2) publication year; (3) study type; (4) continent where the study was conducted; (5) mean age or range; (6) outcome of the diseases; (7) ovaries status (hysterectomy with ovarian preservation; hysterectomy with unilateral oophorectomy; hysterectomy with bilateral oophorectomy; hysterectomy with oophorectomy); (8) age at operation; (9) OR , RR orHR with 95% CI including accompanying oophorectomy or not and age at operation; (10) case number and sample size; (11) adjusted covariates. If more than one RRs provided, we extracted RRs (95% CI) which controlled the influential confounding factors to the greatest extent. Two investigators (Z.W. and X.L.) independently extracted data and any disagreements were resolved by discussing with the third investigator (D.Z.).