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 University of Washington by I-125 (144 Gy) or Pd-103 (115 Gy) implantation for prostatic carcinoma. These 33 patients comprised 7% of the total implants performed. Each patient underwent a preimplant TRUS study in the lithotomy 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 implantation. Twelve patients were treated with neoadjuvant androgen ablation prior to implantation. The prostate volumes quoted here are those taken after hormonal downsizing. Postimplant axial CT images were digitized to calculate the CT-based target coverage. Preimplant urinary obstructive symptoms were quantified by the criteria of the American Urologic Association. Each patient was contacted at the time of this article preparation to update postimplant morbidity information. In all cases, at least 80% of the postimplant volume was covered, despite a median implant-related volume increase of 15%. Five of the 33 patients' postimplant CT scans showed some degree of incomplete target coverage of the anterior/lateral prostate margin. There was no clear association between inadequate anterior/lateral coverage and the degree of interference. Twelve of the 33 patients developed acute postimplant urinary retention, all occurring within 24 hr of implantation. Within this group of 33 patients with a large prostate volume, there was no relationship between the likelihood of acute or chronic urinary retention and preimplant prostate size or obstructive symptoms. Patients who developed postimplant retention lasting more than one week were generally managed by intermittent self-catheterization. By one month, 85% of patients were catheter-free. Based on the data reported here, we are more inclined to accept patients with a large prostate for implantation without insisting on preimplant size reduction. Int. J. Cancer (Radiat. Oncol. Invest.) 90, 199-205 (2000).