Prognostic effect of lymphadenectomy extent on ovarian cancer：A population-based analysis

Abstract Background Lymph node metastasis has a significant contribution to the prognosis of ovarian cancer but the role of lymphadenectomy is controversial in many previous studies. In this study, we aimed to retrospectively determine the effect of lymph nodes removed on survival. Methods Based on the surveillance, epidemiology, and end results registry (SEER) database, we included ovarian cancer patients with detailed information from 1973 to 2014. We performed a large population-based study to evaluate the role of lymphadenectomy in patients with ovarian cancer. Cox regression was conducted to select the impact factors of prognosis of ovarian cancer underwent lymphadenectomy. Our study analyzed the overall and cause specific survival of 61,169 patients diagnosed with ovarian cancer to determine the impact of the extent of the lymphadenectomy on prognosis and also evaluated the prognostic significance stratified on demographic and clinic pathological characteristics. Results The 5- year overall survival (OS) rates were 39.0%, 55.9% and 67.4% for no lymph nodes, 1 ~ 9 nodes, 10 ~ nodes, respectively (p < 0.001). For cause-specific survival (CSS), they were 39.8%, 58.5% and 70%, respectively (p < 0.001). Multivariate Cox model was used to investigate the role of lymphadenectomy in ovarian cancer on OS and CSS and the results indicated lymphadenectomy had beneficial effect on OS (1 ~ 9 nodes: HR = 0.69, 95% CI: 0.68 ~ 0.71, p < 0.001; 10 ~ nodes:HR = 0.55, 95% CI: 0.53 ~ 0.57, p < 0.001) and CSS (1 ~ 9 nodes: HR = 0.68, 95% CI: 0.66 ~ 0.70, p < 0.001;10 ~ nodes:HR = 0.53, 95% CI: 0.51 ~ 0.54, p < 0.001) and with the increase in the number of lymph nodes, the prognostic effect was better. Furthermore, when stratified by age, marital status, race, stage, grade and histology, more resected nodes were associated with a greater OS and CSS in each stratification. Conclusions Lymphadenectomy was associated with more favorable outcomes in ovarian cancer patients undergoing surgery.