Prognostic significance of radiographic lymph node invasion in contemporary metastatic renal cell carcinoma patients

Abstract

Purpose: To test the prognostic significance of radiographic cN-stage in metastatic renal cell carcinoma (mRCC) patients with low metastatic burden (1 site of metastasis), relying on the Surveillance, Epidemiology, and End Results database (SEER 2010-2020). Methods: Included were mRCC patients with 1 site of metastasis, treated with systemic therapy without cytoreductive nephrectomy (CN). Kaplan-Meier plots and multivariable Cox-regression models addressed cancer-specific mortality (CSM) according to radiographic cN-stage (ccN1 vs. ccN0). Separate subgroup analyses were performed, addressing radiographic N-stage in patients with distinct histology (clear-cell vs. RCC not otherwise specified [RCC NOS]). Results: Of 1756 mRCC patients, 545 (31%) were radiographic cN1. Overall, the median CSM-free survival of the cohort was 11 months. Median CSM-free survival was 8 vs. 14 months in radiographic cN1 vs. cN0 mRCC patients (HR 1.49, P < .0001). In multivariable Cox regression analyses, radiographic cN1 status was an independent predictor of higher CSM (HR 1.39; P = .01). In subgroup analyses, addressing patients with clear-cell histology and patients with RCC NOS separately, radiographic cN1 status remained independently associated with a higher CSM in both groups (clear-cell: HR 1.36; P = .03; RCC NOS: HR 2.06; P = .009). Conclusion: In mRCC patients with low metastatic burden, presence or absence of radiographic lymph node invasion results in a clinically meaningful discrimination between those with poor prognosis and others. In consequence, consideration of radiographic lymph node invasion might be of great value in this specific population of mRCC patients.