Lymph Node Dissection is Not Associated with Improved Survival among Patients Undergoing Cytoreductive Nephrectomy for Metastatic Renal Cell Carcinoma: A Propensity Score Based Analysis.

PURPOSE: The oncologic benefit of lymph node dissection for patients undergoing cytoreductive nephrectomy for metastatic renal cell carcinoma is uncertain. Therefore, we evaluated the association of lymph node dissection with oncologic outcomes among patients undergoing cytoreductive nephrectomy.

MATERIALS AND METHODS: We identified 305 patients treated with cytoreductive nephrectomy for metastatic renal cell carcinoma between 1990 and 2010, of whom 188 (62%) underwent lymph node dissection. Several propensity score techniques were used to evaluate cancer specific and all cause mortality. Internally predicted probabilities for pN1 disease were estimated using logistic regression.

RESULTS: Overall 74 (24%) patients had pN1 disease and median followup was 8.5 years (IQR 5.6-10.7). After propensity score adjustment there were no significant differences in clinicopathological features according to whether lymph node dissection was performed. In the overall cohort lymph node dissection was not significantly associated with cancer specific or all cause mortality using any of the propensity score techniques. Moreover, lymph node dissection was not associated with survival outcomes in patients at increased risk for pN1 disease, including patients with preoperative radiographic lymphadenopathy (cN1) or across increasing probability thresholds for pN1 disease from 0.20 to 0.80. Nodal metastases were associated with more aggressive primary tumor features and significantly shorter cancer specific survival.

CONCLUSIONS: Among patients undergoing cytoreductive nephrectomy for metastatic renal cell carcinoma, lymph node dissection was not associated with improved oncologic outcomes in the overall cohort, for patients with preoperative radiographic lymphadenopathy or across increasing probability thresholds for pN1 disease. These findings suggest that lymph node dissection at cytoreductive nephrectomy does not confer an oncologic benefit by cytoreduction of nodal metastases. The presence of nodal metastases is associated with more aggressive tumor biology.