Radiofrequency Ablation of Renal Tumors: Four-Year Follow-Up Results in 47 Patients

OBJECTIVE: To retrospectively evaluate the intermediate results of radiofrequency ablation (RFA) of small renal masses (SRMs). MATERIALS AND METHODS: Percutaneous or laparoscopic RFA was performed on 48 renal tumors in 47 patients. The follow-up studies included a physical examination, chest radiography, creatinine level, and contrast-enhanced CT or MRI. To confirm the pathologic criteria of complete ablation, 35 patients underwent a follow-up biopsy. Recurrence was defined as contrast enhancement on imaging studies after 3 months, lesion growth at subsequent imaging, or viable cancer cells on follow-up biopsy. RESULTS: Technical success was achieved in 43 (89.6%) of 48 renal tumors. The mean tumor size was 2.3 cm and the mean follow-up period was 49.6 months. Repeated RFA was necessary in 5 tumors due to incomplete ablation. The overall complication rate was 35.8%, of which 96.2% were mild complications. Serum creatinine levels at 12 months after RFA did not differ from those before RFA (1.28 vs. 1.36 mg/dL). Four patients were found to have recurrence at various follow-up intervals, and distant metastasis was not found in any cases. CONCLUSION: RFA appears to be a useful treatment for selected patients with SRMs. Our 4-year follow-up results disclose an excellent therapeutic outcome with RFA, while achieving effective local tumor control.

Radiofrequency Ablation of Unilateral Kidney VX2 Tumors in the Rabbit Model / 대한비뇨기과학회지

PURPOSE: The aim of this study was to evaluate the effectiveness and indication of radiofrequency ablation(RFA) using renal VX2 tumors by implantation of VX2 tumor cells under the renal capsule in rabbits. MATERIALS AND METHODS: Ten rabbits were injected with 30-40microliter VX2 tumor cells(1.2x10(7) viable cells/ml) under the renal capsule of the right kidney by right subcostal incision. On the 14th day after the tumor cells were implanted, we checked for the development of renal tumors, and the sizes and shapes(exophytic or central) of the tumors by the use of computed tomography. We performed RFA in the renal VX2 tumors with a 17G StarBurst electrode through kidney exposure. After the first and third day following RFA, renal function was checked. On the third day, we performed CT and harvested the kidneys for gross and microscopic evaluation. RESULTS: We confirmed the development of renal VX2 tumors in nine cases. Tumor shapes were exophytic in seven cases and central in two cases; the mean size of the tumors was 2.1 cm(range, 1.1-3.8cm). In all tumors, RFA was performed. From the use of enhanced CT after RFA on the third day, all of the lesions treated with RFA showed no enhancement. From the pathological findings, coagulative necroses were seen on all of the lesions treated with RFA. The necrotized tumor size after RFA was not different statistically as measured by CT and a pathological examination (p=0.833) CONCLUSIONS:: In centrally located renal tumors, we experienced thermal injury in pelvocalyceal systems. RFA is an effective method for nephron sparing surgery as the tumor cells completely disappear and there is preserved renal function and the procedure is easy to apply. We suggest that the RFA method for exophytic renal tumors is more effective than other procedures.