Abstract
BackgroundMicrowave ablation (MWA) is used to treat patients with unresectable liver cancer. Our institution applied a novel microwave generator capable of automatically adjusting energy levels based on feedback related to tissue permittivity. This approach is meant to facilitate ablations over larger areas and provide results of greater predictablility. This paper reports on the safety, efficacy, and feasibility of this new system in the treatment of patients with large liver tumors.MethodsBetween July 2012 and December 2012, a total of 23 patients with malignant liver tumors exceeding 4 cm in diameter underwent surgical MWA using a 902–928 MHz generator. The proposed system used a 14-gauge antenna without internal-cooling. Follow up on tumor recurrence was performed using contrast-enhanced computed tomography or magnetic resonance imaging at 1 month and then at 3 month intervals for a period of at least 12 months following ablation.ResultsAmong the cancers treated, 10 were primary hepatocellular carcinomas (HCCs) and 13 were metastatic lesions from primary colorectal cancer (CRLM). The mean tumor size was 5.40 cm (range of 4.0-7.0 cm). A total of 18 patients underwent MWA via open surgery, and 5 received laparoscopic MWA. The mean ablation time was 1982 seconds, with a range of 900-3600 seconds, and the median number of ablation sessions was 2.0 (range of 1–4 sessions). The rate of complete ablation, as defined by a total loss of contrast-enhancement one month post-treatment, was 82.6% (19 of 23 patients), and the rate of local recurrence was 26.3% (5 of 19 patients). For tumors with a diameter of 4.0-7.0 cm, the technical success rate of MWA was higher for HCC patients (70%) than for metastatic liver cancer (53.8%) patients; however, the difference was not statistically significant. All patients survived throughout the observation period, and the morbidity rate was 8.6%.ConclusionsMWA treatment using the proposed system with tissue permittivity feedback control resulted in a high rate of complete ablation and reduced morbidity. This approach proved to be a fast, easy, and effective option for the ablation of large liver cancers, particularly HCCs.
Highlights
IntroductionOur institution applied a novel microwave generator capable of automatically adjusting energy levels based on feedback related to tissue permittivity
Microwave ablation (MWA) is used to treat patients with unresectable liver cancer
These challenges led to the development of local tumor ablation as a treatment for small liver tumors which are not amenable to surgical resection [1]
Summary
Our institution applied a novel microwave generator capable of automatically adjusting energy levels based on feedback related to tissue permittivity This approach is meant to facilitate ablations over larger areas and provide results of greater predictablility. Surgical intervention is the gold standard of treatment for liver cancers; many patients are unable to undergo liver resection due to a diminished hepatic reservoir, the multifocal nature of tumors, or severe comorbidities These challenges led to the development of local tumor ablation as a treatment for small liver tumors which are not amenable to surgical resection [1]. Microwave ablation (MWA) therapy has been widely applied in the treatment of liver and lung tumors [6] In this procedure, microwave radiation creates a hyperthermic zone by agitating dipole water molecule in tissue, thereby increasing kinetic energy in the area. Recent advances in engineering have facilitated the development of advanced MW devices that are capable of performing larger ablations in a shorter period of time, compared with traditional RF systems [7,8]
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