Transurethral radiofrequency thermal ablation of prostatic tissue: a feasibility study in humans

Abstract

Objectives. To evaluate the feasibility and efficacy of ablating prostatic tissue by inducing thermal lesions using radiofrequency (RF) energy delivered transurethrally through electrodes mounted on a Foley-like catheter. Methods. Twenty male patients, candidates for radical cystoprostatectomy to treat bladder carcinoma, underwent RF prostate ablation 1 to 8 days before surgery (mean 2.8). Stainless steel, internally cooled, 2-cm-long electrodes mounted on a Foley-like catheter were used to deliver RF energy to the prostatic tissue. Semicircular electrodes were used in 10 patients (group A) and circular electrodes were used in the remaining 10 patients (group B). The urethral, rectal, and prostatic tissue temperatures were recorded. Histologic step sections were performed on whole mounts of the prostates to define the volume of the thermal lesions. Results. The mean RF energy delivered was 36.5 kJ (range 26.4 to 53.1) in group A and 82.3 kJ (range 38 to 149) in group B. The intraprostatic temperatures were between 44°C and 80°C in group A and between 60°C and 119°C in group B. The urethral and rectal temperatures never exceeded 42°C. No major complications occurred. After the RF procedure, 5 patients who received more than 75 kJ of energy could not void and required catheterization. The mean prostate volume was 11.54 cm 3 for group A and 24.02 cm 3 for group B. The mean volumes of the thermal lesions and their relative percentages in relation to the whole prostate in groups A and B were, respectively, 1.69 cm 3 and 15% and 6.91 cm 3 and 29% ( P = 0.049). Analysis of variance showed a significant correlation between the thermal lesion volume and the energy delivered, regardless of the electrode shape ( P = 0.001). Conclusions. Satisfactory thermal ablation of prostatic tissue can be achieved using RF electrodes mounted on a Foley-like catheter. The procedure is effective, simple, and safe and, therefore, can be used in pilot clinical studies on patients with benign prostatic hyperplasia.