Oncologic Outcomes Following Partial Nephrectomy and Percutaneous Ablation for cT1 Renal Masses

Background: Long-term data comparing partial nephrectomy (PN) and thermal ablation are lacking.

Objective: To update our experience with PN, percutaneous radiofrequency ablation (RFA), and percutaneous cryoablation for cT1 renal masses.

Design, setting, and participants: A total of 1798 patients with primary cT1N0M0 renal masses treated between 2000 and 2011 at Mayo Clinic were identified.

Intervention: Percutaneous ablation versus PN.

Outcome measurements and statistical analysis: Cancer-specific survival (CSS) was estimated using the Kaplan-Meier method. Local recurrence, metastases, and death from renal cell carcinoma (RCC) were compared with propensity-score-adjusted Cox models.

Results and limitations: Among 1422 cT1a patients, 1055, 180, and 187 underwent PN, RFA, and cryoablation with median clinical follow-up of 9.4, 7.5, and 6.3yr, respectively. Comparisons of RFA with PN resulted in hazard ratios (HRs) of 1.49 (95% confidence interval [CI] 0.55-4.04, p=0.4), 1.46 (95% CI 0.41-5.19, p=0.6), and 1.99 (95% CI 0.29-13.56, p=0.5) for local recurrence, metastases, and death from RCC. Comparisons of cryoablation to PN resulted in HRs of 1.88 (95% CI 0.76-4.66, p=0.18), 0.23 (95% CI 0.03-1.72, p=0.15), and 0.29 (95% CI 0.01-6.11, p=0.4) for these same outcomes. Five-year CSS was 99%, 96%, and 100% for PN, RFA, and cryoablation, respectively. Among 376 cT1b patients, 324 and 52 underwent PN and cryoablation with median clinical follow-up of 8.7 and 6.0yr, respectively. Comparisons of cryoablation with PN resulted in HRs of 1.22 (95% CI 0.33-4.48, p=0.8), 0.95 (95% CI 0.21-4.38, p>0.9), and 1.94 (95% CI 0.42-8.96, p=0.4) for local recurrence, metastases, and death from RCC, respectively. Five-year CSS was 98% and 91% for PN and cryoablation, respectively. Limitations include retrospective review and selection bias.

Conclusions: With mature follow-up at a single institution, percutaneous ablation appears to have acceptable results for cT1 renal tumors and is appropriate for patients with a contraindication for surgery. For cT1a patients, clinically relevant differences between PN and ablation are unlikely, and treatment choice should involve shared decision making. For cT1b patients, death from RCC was more common with cryoablation, and large differences in this outcome cannot be ruled out. Further research is needed to confirm the oncologic effectiveness of cryoablation in the cT1b setting.

Patient summary: With appropriate patient triage, partial nephrectomy and percutaneous ablation can be used to treat cT1 renal masses, although additional follow-up and further study are still needed.