Purpose: To present the long-term results and to identify possible risk factors for recurrence after radiofrequency ablation (RFA) for renal tumors.

Patients and Methods: Thirty-one patients with a total of 39 renal tumors ranging from 1.3 to 7.5 cm (mean size 3.1 cm) were treated with RFA using a Rita Medical System model 1500 RF generator attached to a 15-gauge Starburst XL probe under percutaneous CT scan guidance. The average patient age was 61.4 years (range 37–86 y). Indications for RFA were bilateral tumors, presence of serious comorbidities, a high risk of development of additional renal-cell carcimomas, marginal renal function, and patient preference. No tumor was biopsied before treatment; therefore, only local control success rates could be provided. Recurrence was defined as enhancement or lesion enlargement on follow-up CT scan. Statistical analysis was performed to identify possible risk factors for recurrence. Parameters tested were age, sex, and number of ablation sessions, tumor size, location, multiplicity, body mass index, and American Society of Anesthesiologists score.

Results: Initial ablation success rate was 90% and with repeated treatment, a success rate of complete ablation reached 97%. Average follow-up was 61.2 months (range 36–84 mos). Recurrence was seen in four tumors. The risk factor associated with recurrence was tumor size exceeding 4 cm (P < 0.01, relative risk [RR] = 3.31). Overall 3- and 5-year tumor control rate was 92% and 89%, respectively. Tumor size was also predictive for recurrence in the subgroup of 17 patients followed for more than 5 years (P = 0.02, RR = 3.15). Tumor control rate for this subgroup was 90%.

Conclusions: According to our results, larger tumor size was prognostic for recurrence after RFA for renal tumors. This treatment seems to demonstrate excellent tumor control long-term results, comparable to those achieved by nephron-sparing surgery in a selected group of patients.