Treatment Trends and Long-Term Survival Associated with Cryotherapy and Partial Nephrectomy for Small Renal Masses in the National Cancer Database Using Propensity Score Matching

Abstract

Objective: Trends in the utilization of ablative therapy are unknown for the treatment of small renal masses. Our goal is to utilize the National Cancer Database (NCDB) to both assess the utilization of ablative therapies and long-term survival. Materials and Methods: The NCDB captures 70% of all cancer cases in the United States and was queried between 1998 and 2012 for renal cell carcinomas that were treated with ablative therapy, partial nephrectomy (PN), or radical nephrectomy. The analysis was limited to clinical stage T_1a. Propensity score matching was used in 1:1 fashion. Kaplan-Meier survival analysis and a Cox proportional hazards model were used to compare overall survival (OS) for cryotherapy and PN. Results: A total of 119,240 cases of clinical stage T_1a renal masses were treated between 1998 and 2012. Cryotherapy peaked at 927 (9.1%) cases in 2010 and had 913 (8.4%) in 2012. PN accounted for 18% of the cases in 1998, but surpassed the utilization of nephrectomy in 2008. By 2012, PN accounted for 6766 (62%) of renal mass cases. After matching, Kaplan-Meier OS was lower for cryotherapy compared with PN at 24 (94.5% vs 96.5%), 48 (86.8% vs 90.9%), and 96 months (66.0% vs 74.9%). Cryotherapy also had a lower OS (hazard ratio 1.46; p < 0.001) on adjusted analysis. Conclusion: Cryotherapy for small renal masses plateaued at 9% utilization in 2009. Cryotherapy had a lower OS than PN for tumors >2 cm on adjusted analysis, but this result should be used with caution until confirmed in randomized studies.

Keywords: carcinoma; kidney function test; partial nephrectomy; renal cell; robotics.