Does lymph node ratio have any prognostic significance in maximally cytoreduced node-positive low-grade serous ovarian carcinoma?

PURPOSE: To determine the prognostic impact of the lymph node ratio (LNR) in node-positive low-grade serous ovarian cancer (LGSOC). METHODS: We retrospectively reviewed women with LGSOC who had undergone maximal cytoreduction followed by standard chemotherapy in 11 centers from Turkey during a study period of 20 years. Sixty two women with node-positive LGSOC were identified. LNR was defined as the number of metastatic lymph nodes (LNs) divided by the number of total LNs removed. We grouped patients pursuant to the LNR as LNR ≤ 0.09 and LNR > 0.09. The prognostic value of LNR was investigated by employing the univariate log-rank test and multivariate Cox-regression model. RESULTS: With a median follow-up of 45 months, the 5-year progression-free survival (PFS) rates were 61.7% for women with LNR ≤ 0.09 and 32.0% for those with LNR > 0.09 (p = 0.046) whereas, the 5-year overall survival (OS) rates were 72.8% for LNR ≤ 0.09 and 54.7% for LNR > 0.09 (p = 0.043). On multivariate analyses, lymphovascular space invasion (LVSI) (Hazard Ratio [HR] 4.18, 95% confidence interval [CI] 1.88-9.27; p < 0.001), omental involvement (HR 3.48, 95% CI 1.36-8.84; p = 0.009) and LNR > 0.09 (HR 3.51, 95% CI 1.54-8.03; p = 0.003) were adverse prognostic factors for PFS. Additionally, LVSI (HR 6.56, 95% CI 2.33-18.41; p < 0.001), omental involvement (HR 6.34, 95% CI 1.86-21.57; p = 0.003) and LNR > 0.09 (HR 7.20, 95% CI 2.33-22.26; p = 0.001) were independent prognostic factors for decreased OS. CONCLUSION: LNR > 0.09 seems to be an independent prognosticator for decreased survival outcomes in LGSOC patients who received maximal cytoreduction followed by standard adjuvant chemotherapy.