Permanent Interstitial Brachytherapy for Clinically Organ-Confined High-Grade Prostate Cancer With a Pretreatment PSA < 20 ng/mL

Abstract

The objective of this study was to determine the effect of biopsy Gleason score 8 and 9 histology on biochemical outcome following a permanent prostate brachytherapy approach that includes multiple periprostatic seeds and supplemental external beam radiation. Forty-six consecutive T1c-T2b (1997 AJCC) patients with Gleason score 8 and 9 prostate cancer who were either hormone naive (33 patients) or received cytoreductive (< or =6 months) hormonal therapy (13 patients) underwent brachytherapy from June 1995 to November 2000. The median patient age was 69.7 years, with a median pretreatment prostate-specific antigen (PSA) of 7.7 ng/mL. The median follow-up was 58 months (range 27-93 months). Forty-five of the patients were implanted with Pd-103 and 44 received supplemental external beam radiation therapy (45 Gy). Biochemical success was defined by either a PSA < or = 0.4 ng/mL after a nadir or by the ASTRO consensus definition. The actuarial 7-year biochemical disease-free survival was 84.8% using either a PSA < or = 0.4 ng/mL or the ASTRO consensus definition. The median postimplant PSA was less than 0.1 ng/mL for both the hormone naive and hormonally manipulated patients. The utilization of hormonal therapy for 6 months or less duration resulted in a statistically nonsignificant improvement in biochemical outcome (92.3% versus 81.8%, P = 0.393). When stratified by pretreatment PSA, 87.9% of patients with a pretreatment PSA < or = 10 ng/mL and 76.9% with a pretreatment PSA > 10 ng/mL (P = 0.377) remained biochemically free of disease. In multivariate analysis, none of the clinical, treatment, or dosimetric parameters predicted for outcome. Following a permanent prostate brachytherapy approach that used multiple periprostatic seeds, the majority of patients with clinically organ-confined Gleason score 8 and 9 prostate cancer remain biochemically free of disease with identical outcomes for both biochemical definitions of success.