Ultrasound-guided percutaneous radiofrequency ablation of small renal tumors: Clinical results and radiological evolution during follow-up.
BACKGROUND
Treatment of small renal masses with percutaneous radiofrequency ablation (RFA) is under development. Data are limited regarding the oncologic efficacy and complication rates of ultrasound (US)-guided RFA.


OBJECTIVE
To retrospectively analyze results and factors predictive of incomplete ablation and local recurrence in patients treated for small renal tumors with US-guided percutaneous RFA.


METHODS
Forty-one consecutive patients (27 males), mean 70 (40-86) years, with 44 tumors were included. Core biopsies were obtained before treatment. Follow-up was performed with CT or MRI. Tumor diameter, tumor volume, volume of the ablation zone, necrosis index, tumor location, distance from tumor to skin, and BMI were analyzed.


RESULTS
Biopsies showed malignancy in 72%, 10% were benign, and 18% were inconclusive. Thirty-six tumors (82%) were completely ablated after first RFA and 40 tumors (91%) after a second treatment. Mean follow-up was 27 months. Nine completely ablated tumors (23%) showed local recurrence during follow-up, six of them were retreated. Tumor size was significantly larger and mean necrosis index lower in tumors with incomplete ablation compared with those completely ablated initially. In tumors <30 mm, the initial complete ablation rate was 93% and the local recurrence rate during follow-up was 16% (4/25).


CONCLUSIONS
US guidance is feasible for RFA of small renal tumors. However, thorough long-term follow-up appears mandatory, as a substantial proportion of the patients will develop late local recurrence and will need more than one RFA treatment session. Large tumor diameter and volume and a low necrosis index were predictive indicators of incomplete ablation after the first treatment.
Lyrdal
David
D
Department of Urology, Sahlgrenska University Hospital, University of Gothenburg, Sweden.
Andersson
Mats
M
Hellström
Mikael
M
Sternal
Joanna
J
Lundstam
Sven
S
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001706:Biopsy; D017115:Catheter Ablation; D016009:Chi-Square Distribution; D005260:Female; D006801:Humans; D007680:Kidney Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000175:diagnosis / Q000601:surgery; D012086:Reoperation; D012189:Retrospective Studies; D018709:Statistics, Nonparametric; D015996:Survival Rate; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D018084:Ultrasonography, Interventional