Four-year biochemical outcome after radioimmunoguided transperineal brachytherapy for patients with prostate adenocarcinoma

Purpose: To evaluate 4-year biochemical outcomes for patients with prostate adenocarcinoma who underwent radioimmunoguided (Prostascint) permanent prostate brachytherapy. Methods and Materials: Eighty patients with clinical T1C-T3A NxM0 prostate cancer underwent ProstaScint-guided prostate brachytherapy using either ¹⁰³Pd or ¹²⁵I between February 1997 and December 2000. Sixty-seven patients underwent prostate brachytherapy alone, whereas 13 patients received neoadjuvant hormonal manipulation before implantation. Risk factors (RF) included PSA >10, Stage ≥T2b, and Gleason grade ≥7. Sixty patients had low-risk disease (0 RF), 17 were intermediate risk (1 RF), and 3 were high risk (2 RF). Biochemical disease-free survival (bDFS) was calculated using the American Society for Therapeutic Radiology and Oncology (ASTRO) consensus criteria, a PSA cutoff of 1.0 ng/mL, and a PSA cutoff of 0.5 ng/mL. Results: Four-year bDFS for the entire cohort was 97.4% using the ASTRO consensus criteria. Low-risk patients (60) had a 4-year bDFS of 100%; intermediate- and high-risk patients (20 patients) were 89.2%. The hormonally naïve group (67 patients) had a 4-year bDFS of 96.9% and a median PSA nadir of 0.2 ng/mL. Median time to nadir was 19.8 months (range: 1.9-53.2 months). For the neoadjuvant hormonal therapy group (13 patients), ASTRO-defined bDFS was 100%. Overall, 85.2% of patients had a posttreatment PSA ≤1.0 ng/mL, and 75.9% had a PSA ≤0.5 ng/mL at a median follow-up of 36 months. Conclusions: At a median follow-up of 36 months, ProstaScint-guided transperineal brachytherapy results in a high probability of actuarial 4-year biochemical disease-free survival for patients with localized prostate cancer.