Treatment for Localized T1a Clear Cell Renal Cell Carcinoma: Survival Benefit for Cryosurgery and Thermal Ablation Compared to Deferred Therapy.

PURPOSE: To evaluate survival of patients with localized T1a clear cell renal cell carcinoma (ccRCC) who received cryosurgery or thermal ablation compared to deferred therapy.

MATERIALS AND METHODS: We included 733 patients with histopathologically confirmed localized T1a ccRCC who either received cryosurgery (n = 315) or thermal ablation (n = 155), as well as patients who deferred therapy (n = 263) from the 2000-2013 Surveillance, Epidemiology, and End Results Program urinary cancer file. Cox proportional hazard models were used to compare cancer-specific survival (CSS) across subgroups. Sensitivity analyses were conducted to assess potential unmeasured confounding by comorbidities.

RESULTS: Patients treated with cryosurgery and thermal ablation had a statistically significant CSS benefit compared to those who deferred therapy (cryosurgery HR 0.25, 95% CI 0.14-0.45, p < 0.001; thermal ablation HR 0.27, 95% CI 0.13-0.55, p < 0.001, after adjustment for age at diagnosis, tumor grade, and size). There was no significant difference in CSS comparing cryosurgery to thermal ablation (HR 1.03, 95% CI 0.45-2.3, p = 0.95, after adjustment for age at diagnosis, tumor grade, and size). These results proved robust upon sensitivity analyses: After adjustment for comorbidities with varying prevalence assumptions, the corrected hazard ratio (cHR) of cryosurgery versus deferred therapy ranged between HR 0.09 and 0.68.

CONCLUSION: Local ablative techniques provide relevant survival benefit and are preferable alternatives over deferred therapy. Cryosurgery and thermal ablation yield comparable outcomes.

LEVEL OF EVIDENCE: 2b according to the Oxford Centre for evidence-based medicine levels of evidence.