Five-year biochemical outcome following permanent interstitial brachytherapy for clinical T1-T3 prostate cancer

PURPOSE: To evaluate 5-year biochemical disease-free outcome for men with clinical T1b-T3a NxM0 1977 American Joint Committee on Cancer (1997 AJCC) adenocarcinoma of the prostate gland who underwent transperineal ultrasound-guided permanent prostate brachytherapy. METHODS AND MATERIALS: Four hundred twenty-five patients underwent transperineal ultrasound-guided prostate brachytherapy using either 103Pd or 125I, for clinical T1b-T3a NxM0 (1997 AJCC) adenocarcinoma of the prostate gland, from April 1995 to October 1999. No patient underwent pathologic lymph-node staging. One hundred ninety patients were implanted with either 103Pd or 125I monotherapy; 235 patients received moderate-dose external beam radiation therapy (EBRT), followed by a prostate brachytherapy boost; 163 patients received neoadjuvant hormonal manipulation, in conjunction with either 103Pd or 125I monotherapy (77 patients) or in conjunction with moderate-dose EBRT and a prostate brachytherapy boost (86 patients). The median patient age was 68.0 years (range, 48.2-81.3 years). The median follow-up was 31 months (range, 11-69 months). Follow-up was calculated from the day of implantation. No patient was lost to follow-up. Biochemical disease-free survival was defined by the American Society of Therapeutic Radiation and Oncology (ASTRO) consensus definition. RESULTS: For the entire cohort, the 5-year actuarial biochemical no evidence of disease (bNED) survival rate was 94%. For patients with low-, intermediate-, and high-risk disease, the 5-year biochemical disease-free rates were 97.1%, 97.5%, and 84.4%, respectively. For hormone-naive patients, 95.7%, 96.4%, and 79.9% of patients with low-, intermediate-, and high-risk disease were free of biochemical failure. Clinical and treatment parameters predictive of biochemical outcome included: clinical stage, pretreatment prostate-specific antigen (PSA), Gleason score, risk group, age > 65 years, and neoadjuvant hormonal therapy. Isotope choice was not a statistically significant predictor of disease-free survival for any risk group. The median postimplant PSA was < or = 0.2 for all risk groups, regardless of hormonal status. The mean posttreatment PSA, however, was significantly lower for men implanted with 103Pd (0.14 ng/mL) than for those implanted with 125I (0.25 ng/mL), p < or = 0.001. CONCLUSION: With a median follow-up of 31 months, permanent prostate brachytherapy results in a high probability of actuarial 5-year biochemical disease-free survival (DFS) for patients with clinical T1b-T3a (1997 AJCC) adenocarcinoma of the prostate gland, with an apparent plateau on the PSA survival curve.