High-powered microwave ablation of t1a renal cell carcinoma: safety and initial clinical evaluation.
OBJECTIVE
Percutaneous radiofrequency ablation and cryoablation are accepted alternative treatments for small renal cell carcinomas (RCC) in high-risk patients. The recent development of high-powered microwave (MW) ablation offers theoretical advantages over existing ablation systems, including higher tissue temperatures, more reproducible ablation zones, and shorter procedural times. The purpose of this study is to review the feasibility, safety, and early efficacy of a novel high-powered percutaneous MW ablation system to treat RCC.


METHODS
An institutional database identified 53 consecutive patients with biopsy-proven RCC ≤4 cm (55 tumors) who were treated with percutaneous MW ablation using a novel MW ablation system. All patients had percutaneous renal mass biopsy, which identified RCC before ablation. Postprocedure follow-up imaging was performed by contrast-enhanced computed tomography or magnetic resonance imaging.


RESULTS
Mean patient age was 66 years and 81% of patients were male. RCC subtypes included clear cell (n=25), papillary (n=12), and unspecified (n=18) and Fuhrman grades 1, 2, 3, and ungraded in 15, 25, 1, and 14 patients, respectively. The mean tumor diameter was 2.6 cm (range 0.8-4.0 cm). Six low-grade complications were recorded during 53 (11.3%) procedures: five Clavien Grade 1 (urine retention, fluid overload, and atrial fibrillation) and one Grade 2 (hemorrhage requiring transfusion). The postprocedure estimated glomerular filtration rate was not significantly changed from preprocedure levels (median: -1.1%, p=0.10). Median follow-up was 8 months (interquartile range [IQR] 5-18.25) with 0/38 (0%) patients demonstrating evidence of local recurrence or metastasis during surveillance imaging.


CONCLUSIONS
Use of a high-powered MW ablation system for the treatment of T1a RCC is feasible, safe, and efficacious with short-term follow-up. A longer follow-up is warranted to evaluate oncologic outcomes.
1 Department of Radiology, University of Wisconsin , Madison, Wisconsin.
Anna J
AJ
Moreland
Timothy J
TJ
Ziemlewicz
Sara L
SL
Best
J Louis
JL
Hinshaw
Meghan G
MG
Lubner
Marci L
ML
Alexander
Christopher L
CL
Brace
Douglas R
DR
Kitchin
Sean P
SP
Hedican
Stephen Y
SY
Nakada
Fred T
FT
Lee
E Jason
EJ
Abel
D000368:Aged; D001706:Biopsy; D002292:Carcinoma, Renal Cell / Q000473:pathology / Q000628:therapy*; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007680:Kidney Neoplasms / Q000473:pathology / Q000628:therapy*; D008279:Magnetic Resonance Imaging; D008297:Male; D008872:Microwaves / Q000009:adverse effects / Q000627:therapeutic use*; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local; D012449:Safety; D016896:Treatment Outcome