PERCUTANEOUS TRANSPERINEAL RADIOFREQUENCY ABLATION OF PROSTATE TUMOR - SAFETY, FEASIBILITY AND PATHOLOGICAL EFFECTS ON HUMAN PROSTATE-CANCER

Objective To evaluate the safety of radiofrequency (RF) energy deliver ed interstitially in patients with prostate cancer scheduled for radic al prostatectomy and to correlate the proposed theoretical lesion size with the pathological findings. Patients and methods Radiofrequency i nterstitial tumour ablation (RITA) was performed in 15 patients with l ocalized prostate cancer before radical surgery, RF energy was deliver ed to the prostate by active needle electrodes (monopolar or bipolar) placed transperineally under transrectal ultrasonography guidance. Nee dle electrodes were used with different configurations and in some cas es were covered by retractable shields to vary the length and circumfe rence of the thermal lesions created, In eight patients, the procedure was performed immediately before radical prostatectomy, in six RITA w as performed under spinal anaesthesia 1 week before surgery and in one patient, no surgery was performed but the patient was followed by ser ial determinations of prostate specific antigen (PSA), At least two le sions were created in each prostate, including both capsule and periph eral zones, NADPH and haematoxylin & eosin (H&E) staining were used to assess the extent of the necrotic lesion in the radical prostatectomy specimen. Results The mean energy delivered was 10.5 kJ, with central temperatures reaching up to 105 degrees C during 12 min of ablation; rectal temperature remained at <38 degrees C. There were no complicati ons. Macroscopic examination showed well-demarcated lesions including the prostatic capsule, up to 2.2 x 1.5 x 4.5 cm, With monopolar energy , the observed lesion size was comparable to the predicted 2 x 2 x 2 c m lesion, while with bipolar energy, lesion size was related to inter- needle distance and uncovered needle length. Microscopic examination s howed clearly delineated lesions both with NADPH (in prostates immedia tely removed after surgery) and H&E (at 1 week after RITA) staining. T he lesion size observed on pathological analysis correlated with the p redicted lesion size. In one patient, no residual cancer was found in the specimen. In the patient whose entire prostate was targeted and fo llowed by serial PSA measurements, the latter were undetectable at 3 m onths of follow-up. Conclusion Transperineally delivered RF energy is capable of safely creating extensive coagulative necrotic lesions in p rostate cancer tissue, in a reproducible and controlled manner, The re sults presented here provide basic information for the potential futur e application of this form of energy for localized prostate cancer.