Defining the implant treatment volume for patients with low risk prostate cancer: Does the anterior base need to be treated?

Purpose: An increased incidence of acute urinary retention has been reported after interstitial prostate radiation therapy when the anterior base of the prostate gland receives 100% of the prescription dose. The frequency of prostate cancer in this location as a function of the pre-treatment prostate specific antigen (PSA), biopsy Gleason score, and 1992 American Joint Commission on Cancer Staging (AJCC) was determined. Methods and Materials: One hundred four men treated at the Brigham and Women's Hospital with radical prostatectomy for clinically localized prostate cancer between 1995-1996 comprised the study population Prostatectomy specimens were whole mounted and the location of each tumor foci enumerated. Results: Of 269 foci of prostate cancer found in 39 low-risk prostate cancer patients (PSA < 10 ng/ml, biopsy Gleason score less than or equal to 6, and 1992 AJCC clinical stage T-1c,T-2a), a single focus (0.37%) was noted in the anterior base. Conversely, 20/355 (5.6%) and 18/251 (7.2%) tumor foci were noted in the anterior base in 43 patients with intermediate risk and 24 patients with high-risk disease, respectively. Conclusions: A new definition of the treatment volume excluding the anterior base for low-risk prostate cancer patients may be justified. (C) 1999 Elsevier Science Inc.