[Two cases of cavity formation in prostatic urethra after transurethral microwave thermotherapy (TUMT) with Prostatron].

The Prostatron device, developed by Dr. Devonec, provides microwave heating of the prostate and simultaneous conductive cooling of the urethra. Treatment with Prostatron (transurethral microwave thermotherapy: TUMT) of BPH can be performed in a single session, and the urethra, the rectum and the surrounding tissue are protected with the temperature monitoring system. TUMT with Prostatron may be more suitable for a small adenoma with mild symptoms than a large adenoma with severe symptoms, because objective improvement is rarely observed compared with subjective improvement. We have treated 40 cases of BPH with Prostatron (Prostasoft 2, max. energy: 50 watt, max. urethral temperature: 44.5 degrees C, max. rectal temperature: 42.5 degrees C) since March 1993. Among them, there were 2 cases of large cavity formation involving the prostatic urethra. With cavity formation, TUMT may have its place in the treatment of a large adenoma with severe urinary symptoms, but loses its advantage in the prevention of persistent urinary infection and retrograde ejaculation, especially in the treatment of a small adenoma in a younger patient with mild urinary symptoms. It is unknown why such cavity formation occurred only in 2 patients among 40 equally treated cases, but the causes of cavity formation and safety of TUMT should be evaluated again, even though no injury to the rectum and the external urethral sphincter were detected. We report these 2 cases, and causes of cavity formation and discuss the prospects of TUMT.