Valuation of lymph node dissection in localized high-risk renal cell cancer using X-tile software

Abstract

Purpose: Attempt to group the number of lymph nodes in a more ideal way to assess the value of lymph node dissection (LND) in the treatment of localized high-risk renal cell cancer (LH-RCC).

Methods: The Surveillance, Epidemiology, and End Result database (SEER) was used to analyze LH-RCC patients who undergoing radical nephrectomy (RN) from 2011 to 2015. The X-tile software was performed to calculate the optimal grouping cut-off points for the number of removed lymph nodes and positive lymph nodes. The Nomogram model was constructed by R language to visually present survival rates of patients.

Results: Among 4917 cases of LH-RCC patients undergoing RN, there were 1835 patients treated with LND (37.32%) with the average survival time (AST) of 43.10 months (95% CI 41.91-44.29), which was superior than 40.52 months of patients who did not have LND (95% CI 39.26-41.78) (P < 0.01). The mortality risk of patients with ≥ 3 removed nodes was 0.75 times that of patients with 1-2 removed nodes (95% CI 0.62-0.99, P < 0.01). For overall survival (OS), the hazard ratio of ≥ 5 positive nodes, 1-4 positive nodes, and 0 positive node was 3.04, 2.37, and 1.00, respectively. The Nomogram model can evaluate the 1 year, 2 year, and 3 year survival rates of LH-RCC patients undergoing RN with the internal validation C-index of 0.73.

Conclusion: LH-RCC patients with ≥ 3 removed lymph nodes and fewer positive lymph nodes are expected to have better long-term survival. LND is not only helpful for tumor staging of LH-RCC, but also valuable for long-term survival.

Keywords: Localized high-risk renal cell cancer; Lymph node dissection; SEER database; Survival; X-tile.