Hepatic tumor ablation with clustered microwave antennae: the US Phase II trial.
BACKGROUND
Thermal ablation techniques have become important treatment options for patients with unresectable hepatic malignancies. Microwave ablation (MWA) is a new thermal ablative technique that uses electromagnetic energy to produce coagulation necrosis. We report outcomes from the first clinical trial in the United States using MWA and a 915 MHz generator.


METHODS
Patients with unresectable primary or metastatic liver cancer were enrolled in a multi-institutional trial from March 2004 through May 2006. Demographic information, diagnosis, treatment, and outcomes were documented.


RESULTS
Eighty-seven patients underwent 94 ablation procedures for 224 hepatic tumors. Forty-two ablations (45%) were performed open, 7 (7%) laparoscopically, and 45 (48%) percutaneously. The average tumor size was 3.6 cm (range 0.5-9.0 cm). Single antenna ablation volumes were 10.0 ml (range 7.8-14.0 ml), and clustered antennae ablation volumes were 50.5 ml (range 21.1-146.5 ml). Outcome variables were measured with a mean follow-up of 19 months. Local recurrence at the ablation site occurred in 6 (2.7%) tumors, and regional recurrence occurred in 37 (43%) patients. With a mean follow-up of 19 months, 41 (47%) patients were alive with no evidence of disease. There were no procedure-related deaths. The overall mortality rate was 2.3%.


CONCLUSIONS
Microwave ablation is a safe and effective technology for hepatic tumor ablation. In our study, clustered antennae resulted in larger ablation volumes. Further studies with histological confirmation are needed to verify clinical results.
Iannitti
David A
DA
Division of Gastrointestinal and Minimally Invasive Surgery, Carolinas Medical Center, Charlotte, NC 28203, USA. David.Iannitti@carolinashealthcare.org
Martin
Robert C G
RC
Simon
Caroline J
CJ
Hope
William W
WW
Newcomb
William L
WL
McMasters
Kelly M
KM
Dupuy
Damian
D