Gleason Score 7 Prostate Adenocarcinoma Treated with Definitive Low-Dose-Rate Brachytherapy

Abstract

implantation alone with prescription dose of 144Gy. The rest of intermediate-risk cases and high-risk cases (PSAO20 or GSO7 or T3a) were treated with seed implantation (prescription dose 100 to 110Gy) followed by EBRT (1.8Gy x 25 5 45Gy) starting from a month after the seed implantation. Post-treatment dosimetric analysis was performed on each case based on CT-scan images a month after BT. Phoenix definition (nadirþ2) was used toanalyze biological failure (BF), and the time to BF was determined with Kaplan-Meier’s analysis. Cox regression analysis was used to evaluate the risk factors of treatment failure. Results: Five-year overall survival ratewas 97.6% and 5-year freedom from BF rate was 92.0% for all patients. Five-year freedom from BF rate for lowrisk, intermediate-risk and high-risk cases were 95.9%, 92.1% and 82.3%, respectively. Local recurrence, that was evaluated by biopsy or MRI images, was found in 1.09% (5/458), 1.30% (9/693), and 2.80% (4/143) in low-, intermediateand high-risk cases, respectively. Metastatic lesions were found in 0.44% (2/458), 2.74% (19/693), and 8.39% (12/143) in low-, intermediateand high-risk cases, respectively. In multivariate analyzes, iPSA (p50.036), GS (p50.00) and T stage (p50.00) were significantly associated with BF. T stage was the only factor that significantly associated with clinical failure (hazard ratio: 1.205, p50.001). Conclusions: Initial experiences of BT for prostate cancer in Japan showed satisfactory results. Metastatic lesions were more likely to be found in the high-risk cases, but local control of the disease was fine in any risk groups. Overall, BT showed favorable results even for the high-risk cases.