3:54 PM Abstract No. 270 Percutaneous cryoablation for stage 1 renal cell carcinoma: 10-year prospective oncologic outcomes and comparison with matched surgical cohorts from the National Cancer Database

Abstract

Ablation is increasingly recognized as a curative therapy for select patients with stage 1 renal cell carcinoma (RCC). Current literature on ablation outcomes is largely retrospective in nature and limited by lack of long-term follow-up and biopsy confirmation of disease in many cases. The objective of this study was to address those limitations and rigorously assess long-term oncologic outcomes in a prospective cohort after cryoablation for Stage 1 RCC. This was an IRB-approved prospective 10-year study of 134 consecutive patients treated with CT-guided cryoablation for biopsy-proven RCC. Overall survival (OS), recurrence-free survival (RFS), and disease-specific survival (DSS) were estimated using interval censored data and Turnbull’s nonparametric survival analysis methods. Survival was compared to available postnephrectomy outcomes in matched subgroups from the National Cancer Database. Long-term renal function was also estimated using serum creatinine (sCr), glomerular filtration rate (GFR), and new hemodialysis requirement during follow-up. Of 134 patients, 19 (14%) were Stage 1B. Median tumor size was 2.8 ± 1.4 cm. At 5 and 10 years, respectively, OS was 86.5 ± 3.2% and 72.1 ± 5.4%; RFS was 85.0 ± 2.9% and 69.1 ± 5.1%; DSS was 94.3 ± 2.1% at both time points. Cryoablation outperformed both partial and radical nephrectomy in terms of OS based on matched subgroup data from the NCDB. In subgroup analysis, the Kaplan-Meier OS and RFS curves dipped significantly with advanced age above 80 years, and both 5- and 10-year DSS rose to 100% with age above 85. No significant changes in sCr or GFR were observed at 10 years. The 10-year unadjusted hemodialysis risk for patients with normal baseline creatinine was 2.3%. This 10-year prospective study in patients with Stage 1 RCC shows that image-guided, percutaneous cryoablation provides long-term survival and renal outcomes at least equivalent to that of nephrectomy, with an improved peri-operative risk profile. Subgroup analysis suggests that cryoablation does not confer survival benefit to patients diagnosed with Stage 1 RCC above the age of 80.