Biochemical outcome for hormone-naive patients with high-risk prostate cancer managed with permanent interstitial brachytherapy and supplemental external-beam radiation

PURPOSE The purpose of this article is to report the 5-year biochemical disease-free outcome for hormone-naive patients with high-risk disease who underwent permanent prostate brachytherapy. Multiple clinical and treatment parameters were also evaluated to determine whether any of these influence biochemical outcome. MATERIALS AND METHODS Sixty-six hormone-naive patients underwent transperineal ultrasound-guided permanent prostate brachytherapy with generous periprostatic margins by use of either Pd-103 or I-125 for high-risk prostate cancer from April 1995 to October 1999. High-risk patients presented with two or three of the following risk factors: Gleason score greater than or equal to7, prostate-specific antigen greater than or equal to10 ng/mL, and clinical stage greater than or equal to T2b, 1997 AJCC. No patient underwent pathological lymph node staging. Only one patient was implanted with monotherapy, whereas 65 patients received supplemental external-beam radiation therapy before a prostate brachytherapy boost. The median patient age was 69 years (range, 50-81 years). No patient was lost to follow-up. The mean follow-up and median follow-up were 53.2 +/- 14.9 months and 53.7 months, respectively (range, 19.8-79.7 months). Follow-up was calculated from the day of implantation, Biochemical disease-free survival was defined by the American Society of Therapeutic Radiology and Oncology consensus definition. Clinical parameters evaluated for biochemical disease-free survival included patient age, clinical staged Gleason score, and pretreatment prostate-specific antigen. Treatment parameters included use of supplemental external-beam radiation therapy and choice of isotope, RESULTS The 5-year actuarial biochemical disease-free survival rate was 79.9%. In multivariate analysis, preimplantation prostate-specific antigen (P = 0.008) was the only clinical or treatment parameter that predicted for biochemical failure. The mean and median posttreatment prostate-specific antigen levels were 0.13 +/- 0.22 ng/mL and < 0.1 ng/mL, respectively. DISCUSSION At a median follow-up of 53,7 months, hormone-naive patients with high-risk disease who undergo permanent prostate brachytherapy have a high probability of 5-year biochemical disease-free survival and an apparent plateau on the biochemical disease-free survival curve.