Data abstraction
Data abstraction was done using a standardized spreadsheet designed for the study. Data include study characteristics (authors, year of publication, study setting, type of the study, comparison arms, and sample size), patient characteristics (selection frame, patient demographics, disease stage, pathological grade, histologic type, serum CA125), surgical management, tumor size, intraoperative findings, number of removed lymph nodes, lymph nodes status, residual disease after surgery, adjuvant or neoadjuvant treatment and duration of follow up. The data were abstracted from article text, tables, and figures. Quality assessment of included studies was assessed using US National Heart, Lung and Blood Institute Quality Assessment Tool (9).