Systematic lymphadenectomy in the treatment of epithelial ovarian cancer: a meta-analysis of multiple epidemiology studies

Objective: To evaluate the role of systematic lymphadenectomy in epithelial ovarian cancer by comparing 5-year overall survival rates between systematic and unsystematic lymphadenectomies. Methods: A literature search of the Pubmed, Embase and Cochrane Library databases was performed up to 2014. Two authors independently determined the eligibility of the articles and extracted the available data. The role of systematic lymphadenectomy in epithelial ovarian cancer was analyzed by combining all qualified individual studies using afixed-effect model. Then, subgroup analysis was performed by dividing articles according to type, cancer stage and residual tumor. Finally, heterogeneity and publication bias in all enrolled studies were assessed using Higgins I-2 statistics and funnel plots, respectively. Results: Fourteen relevant studies including 3488 subjects were included in the analysis. The value of pooled relative ratios of all qualified studies revealed that the 5-year overall survival rate in the lymphadenectomy group was higher than that in the unsystematic lymphadenectomy group (relative ratio = 1.08; P = 0.001), which was duplicated in the subgroup analysis of observational studies (relative ratio = 1.07; P = 0.002) and advanced stage (relative ratio = 1.21; P = 0.012) epithelial ovarian cancer. No significant differences were observed in randomized controlled trials (relative ratio = 1.01; P = 0.858), early stage epithelial ovarian cancer (relative ratio = 1.06; P = 0.064) or patients with residual tumor <= 2 cm (relative ratio = 1.05; P = 0.125). The heterogeneity and publication bias in the enrolled studies were within acceptable thresholds. Conclusions: Lymphadenectomy can improve the 5-year overall survival rate in advanced stage epithelial ovarian cancer but not in early stage epithelial ovarian cancer or in patients with residual tumor <= 2 cm.