Ten-year outcomes of I125 low-dose-rate brachytherapy for clinically localized prostate cancer: a single-institution experience in Japan

To report 10-year outcomes of patients treated with I-125 low-dose-rate brachytherapy (BT) for clinically localized prostate cancer. A group of 1,060 patients with clinically localized prostate cancer treated with I-125 BT between March 2004 and December 2013 at the Yokohama City University Hospital were identified. The records of 743 patients with a minimum of 2 years of follow-up were reviewed. Cohorts were categorized according to National Comprehensive Cancer Network risk classification, and biochemical outcomes plus overall survival were examined. Biochemical failure was defined as nadir prostate-specific antigen (PSA) level + 2 ng/mL. Univariate and multivariate Cox proportional hazards were used to determine predictors of biochemical failure. A total of 743 patients met the criteria with a median follow-up of 54.6 months (range 24-114 months). The median age was 70 years (range 48-83). The 5- and 7-year overall survival rates were 98.8 and 97.6 %, and the 5- and 7-year biochemical failure-free survival rates were 92.6 and 91.0 %, respectively. With regard to distant metastases and survival, the 5- and 7-year metastatic-free survival rates were 98.2 and 95.9 %, respectively. A multivariate analysis revealed that initial PSA (p = 0.005; HR 1.097, 95 % CI 1.028-1.170), age (p = 0.001; HR 0.931, 95 % CI 0.893-0.971), and T stage (T1c vs. T2a) (p = 0.002; HR2.417, 95 % CI 1.319-4.267) were independent predictors of biochemical failure. I-125 low-dose-rate BT resulted in excellent survival and morbidity outcomes for localized prostate cancer at a single institution. Further studies are needed to obtain long-term outcomes.