MP84-06 HISTOLOGY IMPACTS SURVIVAL OUTCOMES IN CONTEMPORARY PATIENTS UNDERGOING PRIMARILY PARTIAL NEPHRECTOMY FOR RENAL CELL CARCINOMA

Abstract

INTRODUCTION AND OBJECTIVES: Renal cell carcinoma (RCC) histology may impact survival in high tumor stages only, reflected in the absence of prognostic value in patients undergoing partial nephrectomy (PN). However, these observations derived from cohorts where PN was performed mostly out of necessity. With the advent of PN, the question remains whether histology holds prognostic significance in contemporary patients. We address this question in patients undergoing radical nephrectomy (RN) and PN for clinically localized RCC. METHODS: 3348 patients underwent surgery for RCC at a tertiary referral center from 2002 to 2014. Patients aged <18 years (n1⁄42), with metastatic disease at diagnosis (n1⁄4251), bilateral tumors or hereditary RCC (n1⁄4149), or with missing date of last follow-up (n1⁄41) were excluded, leaving 2945 patients. To test whether histology predicted recurrence-free survival (RFS) and overall survival (OS) differently based on surgical technique (RN vs PN), we included the interaction term between surgical technique and histology in Cox proportional hazards models. RESULTS: 863 (29%) patients underwent RN and 2082 (71%) underwent PN. Median follow-up among living patients was 3.7 years. There was no significant interaction between surgical technique and histology for either RFS or OS, indicating that there is no evidence that histology predicts outcomes differently for patients receiving RN or PN. Patients with chromophobe and papillary RCC demonstrated lower risk of RFS compared to clear cell RCC (HR 0.38, 95%CI 0.21-0.72 and HR 0.40, 95%CI 0.22-0.76, respectively), patients with sarcomatoid features and unclassified RCC had higher risk (HR 3.47, 95%CI 2.21-5.45 and HR 1.73, 95%CI 1.09.2.75, respectively). With regard to OS, chromophobe RCC was associated with a significantly lower risk of death than clear cell RCC (HR 0.58, 95%CI 0.35-0.94), while there was no significant difference in risk between papillary and clear cell RCC (HR 0.95, 95%CI 0.68-1.33). Patients with sarcomatoid features and unclassified RCC had a higher risk of death compared to those with clear cell RCC (HR 3.28, 95% CI 2.06, 5.23 and HR 1.68, 95%CI 1.162.45, respectively). CONCLUSIONS: In contemporary patients treated primarily with PN for RCC, histology remains a significant predictor of RFS and OS, regardless of the type of surgery. While it is known that histologic features of RCC reflect genetic distinction, underlying differences in biological behavior also exist. Research exploring the mechanisms underlying these differences may unveil novel, individualized therapies.