Mp22-16 Cytoreductive Partial Nephrectomy for Small Primary Tumors Improves Overall Survival in Metastatic Kidney Cancer

Abstract

INTRODUCTION AND OBJECTIVES: Cytoreductive radical nephrectomy (RN) improves survival in select patients with metastatic renal cell carcinoma (mRCC). For smaller primary tumors, however, it is unknown whether cytoreductive partial nephrectomy (PN) compromises oncologic efficacy. Our objective was first to evaluate whether the size of the primary tumor is associated with overall survival (OS) in mRCC. Second, we sought to evaluate whether PN had equivalent OS compared with RN in patients with small primary tumors.METHODS: We queried the National Cancer Database from 2004-2013 and identified patients who underwent cytoreductive PN or RN for mRCC. Tumor size was categorized as T1a, T1b, and T2a. Rates of cytoreductive PN were analyzed over time. Descriptive statistics were used to compare patient demographics and tumor characteristics by surgical procedure (PN vs. RN) and tumor size. Kaplan-Meier survival analysis was used to compare OS. Multivariable Cox proportional hazards models were used to determine the effect of surgery type on OS.RESULTS: A total of 4,464 patients met our inclusion criteria, with 94.4% undergoing a RN and 5.6% undergoing a PN. Rates of cytoreductive PN increased over time from 3.2% in 2004 to 9.4% in 2013. One-year OS was 71.3%, 69.2%, and 61.7% in patients with T1a, T1b, and T2a primary tumors, respectively (log rank test: p<0.001). In a multivariable model controlling for age, Charlson-Deyo score, histology, receipt of systemic treatment, metastasis location, and surgical procedure, T2a was a predictor of worse OS (HR 1.2, 95% CI 1.07-1.33). OS was then evaluated in patients who received a PN vs. RN in the entire cohort, as well as within each primary tumor Tstage (Figure 1). Patients who underwent PN had significantly improved OS, which was significant for T1a and T1b tumors (p<0.01) but not for larger T2a tumors (p¼0.74). This was maintained in a Cox multivariable model. CONCLUSIONS: In patients with mRCC undergoing cytoreductive nephrectomy, primary tumor size affects OS. PN was associated with longer OS in select groups of patients with small primary tumors. Further studies are needed to establish patient selection criteria in order to optimize the surgical care of patients with mRCC.