Transperineal brachytherapy in patients with large prostate glands

The purpose of this study is to help clarify the use of prostate size as a selection factor for prostate brachytherapy. From 1997 to 1998, 33 patients with a TRUS-based prostate volume greater than 50 cc were treated at the U niversity of Washington by I-125 (144 Gy) or Pd-103 (115 Gy) implantation f or prostatic carcinoma. These 33 patients comprised 7% of the total implant s performed. Each patient underwent a preimplant TRUS study in the Lithotom y position, taking serial axial images of the prostate at 0.5 cm intervals from the base of the gland to the apex. The contours on the preimplant TRUS images were used to calculate the prostate volumes reported here. Only one patient received supplemental external beam irradiation prior to implantat ion. Twelve patients were treated with neoadjuvant androgen ablation prior to implantation. The prostate volumes quoted here are those taken after hor monal downsizing. Postimplant axial CT images were digitized to calculate t he CT-based target coverage. Preimplant urinary obstructive symptoms were q uantified by the criteria of the American Urologic Association. Each patien t was contacted at the time of this article preparation to update postimpla nt morbidity information. In all cases, at least 80% of the postimplant vol ume was covered, despite a median implant-related volume increase of 15%. F ive of the 33 patients' postimplant CT scans showed some degree of incomple te target coverage of the anterior/lateral prostate margin. There was no cl ear association between inadequate anterior/lateral coverage and the degree of interference. Twelve of the 33 patients developed acute postimplant uri nary retention, all occurring within 24 hr of implantation. Within this gro up of 33 patients with a large prostate volume, there was no relationship b etween the Likelihood of acute or chronic urinary retention and preimplant prostate size or obstructive symptoms. Patients who developed postimplant r etention lasting more than one week were generally managed by intermittent self-catheterization. By one month, 85% of patients were catheter-free. Bas ed on the data reported here, we are more inclined to accept patients with a large prostate for implantation without insisting on preimplant size redu ction. (C) 2000 Wiley-Liss, Inc.