Prognostic value of lymph node ratio in patients with advanced epithelial ovarian cancer

•Lymph node status is a prognostic factor in ovarian cancer.•Lymph node ratio reflects lymph node spread and surgical extent.•Lymph node ratio predicts overall survival more concisely.

ObjectiveLymph node status is an established prognostic factor in epithelial ovarian cancer (EOC). Lymph node ratio (number of positive LN/number of resected LN) reflects both qualitative and quantitative lymph node spread as well as surgical effort and extent of disease. We evaluated whether LNR is a more precise prognostic factor than conventional lymph node status in patients with EOC.MethodsThe present retrospective study includes 809 patients with EOC, who underwent primary cytoreductive surgery between 2000-2013. Clinico-pathological parameters and survival data were extracted from a prospectively maintained tumor registry database. The optimal cut-off point for LNR was calculated by using Martingale residuals. Survival analyses were calculated using Kaplan-Meier method and Cox regression models.ResultsLymphadenectomy was performed in 693 (85.7%) out of 809 patients. Median number of removed LN was 64 (IQR 25-75%: 39-84). LNR of 0.25 was identified as the optimal prognostic cut-off value. The estimated 5-year-OS rates were 69.3% for patients with node-negative EOC compared to 33.1% for patients with any lymph node metastasis (p < 0.001). The estimated 5-year-OS rates were 42.5% for patients with LNR ≤ 0.25, and 18.0% for patients with LNR > 0.25 (p < 0.001). Additionally in multivariate analysis LNR > 0.25 was approved to be an independent prognostic factor for overall survival (adjusted HR 1.44, 95% CI 1.04-2.00; p = 0.028).ConclusionLNR more precisely predicts overall survival than conventional lymph node status in EOC patients undergoing primary debulking surgery.