TRANSURETHRAL MICROWAVE THERMAL ABLATION FOR BENIGN PROSTATIC HYPERPLASIA 119

low figure and it certainly means that patients should be warned about it before the treatment.

The absence of a sham operated or nonoperated control group means that these results should be viewed as an indicator pointing us towards what appears to be a good new technology. It is to be hoped that the authors will now move to a comparative trial not necessarily against transurethral prostatectomy but rather against some of the other heat based treatments. The results would be interesting.

John M . Fitzpatrick Departments of Urology and Surgery Mater Misericordiae Hospital and University College Dublin, Ireland

REPLY BY AUTHORS

How many cases should one treat before reporting on the efficacy and safety of a new technology for symptomatic BPH? Most reports have insufficient rather than too many numbers. Randomized com- parative studies are an important part of the assessment of new

treatment options, and such studies comparing treatment with the T3 device to sham operation and transurethral resection of the prostate were done after the initial results of the present study indicated its safety and efficacy. The number of patients in the current study was believed to be necessary, since we wanted to assess a number of variables, such as duration of catheterization (at the discretion of each center), analgesic requirement, some modifi- cations to the catheter and whether pretreatment parameters could predict likelihood of response.

The mechanism of action of transurethral microwave thermoabla- tion is unclear. This technology aims to preserve the urethra, and a cavity was seen within the prostatic urethra in only a minority of patients. Destruction of nerve fibers and increased distensibility of the urethra secondary to tissue necrosis may have a part. Regarding the 29% of patients who found the procedure moderately to severely painful, an aim of the study was to assess the extent of discomfort, and so routine preoperative analgesia was not given. The routine use of analgesia brfore treatment may well help to prevent or decrease this discomfort.