The role of lymph node dissection in the management of renal cell carcinoma: a systematic review and meta-analysis.

Our objective was to evaluate the role of retroperitoneal lymph node dissection (LND) in non-metastatic (M0) and metastatic (M1) renal cell carcinoma (RCC). We searched Medline, EMBASE, Web of Science and Scopus from database inception to 29 August 2017 for studies of patients who underwent partial or radical nephrectomy for M0 or M1 RCC. Two investigators independently selected studies for inclusion. Risk of bias was assessed using the Newcastle-Ottawa scale, Cochrane Collaboration tool and National Heart, Lung and Blood Institute Quality Assessment Tool. Random effects meta-analysis was performed for all-cause-mortality. The GRADE approach was used to characterize quality of evidence. A total of 51 unique studies were included in the qualitative systematic review. Risk of bias was low in 41/51 (80%) studies. LND was not associated with all-cause mortality in either M0 (hazard ratio [HR] 1.02, 95% confidence interval [CI] 0.92-1.12; I2 = 0%; four studies), M1 (HR 1.04, 95% CI 0.83-1.29; I2 = 0%; two studies), or pooled M0 and M1 settings (HR 1.00, 95% CI 0.92-1.09; I2 = 0%; seven studies), with no statistically significant differences according to M stage subgroups (P = 0.50). In the three studies that examined M0 subgroups with a high risk of nodal metastasis, LND was not associated with improved oncological outcomes. Studies on the association of extent of LND with survival reported inconsistent results. Meanwhile, a small proportion of patients with pN1M0 disease demonstrate durable long-term oncological control after surgery, with 10-year cancer-specific survival of 21-31%. Nodal involvement is independently associated with adverse prognosis in both M0 and M1 settings. GRADE quality of evidence was moderate or low for the outcomes examined. Although LND yields independent prognostic information, the existing literature does not support a therapeutic benefit to LND in either M0 or M1 RCC. High-risk M0 patient groups warrant further study, as a subset of patients with isolated nodal metastases experience long-term survival after surgical resection.