12-year outcomes following permanent prostate brachytherapy in patients with clinically localized prostate cancer

Purpose: We reviewed the outcomes in men treated with permanent prostate brachytherapy (PPB). Material and Methods: A total of 1,449 consecutive patients with a mean age of 68 years treated with PPB between 1992 and 2000 and mean pretreatment prostate specific antigen (PSA) 10.1 ng/ml were included in this study. Of the patients 55% presented with Gleason 6 tumors and 28% had Gleason 7 disease. A total of 400 patients (27%) were treated with neoadjuvant hormones and 301 (20%) were treated in combination with external radiation plus PPB. Several biochemical freedom from recurrence (BFR) definitions were determined. Statistical analysis consisted of log rank testing, Kaplan-Meier estimates and Cox regression analysis. Results: Median followup was 82 months with 39 patients at risk at for 144 months. Overall and disease specific survival at 12 years was 81% and 93%, respectively. The 12-year BFR was 81%, 78%, 74% and 77% according to the American Society for Therapeutic Radiology and Oncology (ASTRO), ASTRO-Kattan, ASTRO-Last Call and Houston definitions, respectively. The 12-year ASTRO-Kattan BFR using risk stratification was 89%, 78% and 63% in patients at low, intermediate and high risk, respectively (p = 0.0001). Multivariate analysis identified the dose that 90% of the target volume received (p < 0.0001), pretreatment PSA (p = 0.001), Gleason score (p = 0.002), the percent positive core biopsies (p = 0.037), clinical stage (p = 0.689), the addition of hormones (p = 0.655) and the addition of external radiation (p = 0.724) for predicting BFR-ASTRO. Five-year disease specific survival was 44% in patients with a PSA doubling time of less than 12 months vs 88% in those with a PSA doubling time of 12 months or greater (p = 0.0001). Conclusions: PPB offers acceptable 12-year BFR in patients who present with clinically localized prostate cancer. Implant dosimetry continues as an important predictor for BFR, while the addition of adjuvant therapies such as hormones and external radiation are insignificant. In patients who experience biochemical failure it appears that PSA doubling time is an important predictor of survival.