Iodine monotherapy for Japanese men with low- and intermediate-risk prostate cancer: outcomes after 5 years of follow-up

Data from 305 Japanese men with low-risk (n = 175) or intermediate-risk (n = 130) prostate cancer who underwent [sup.125]I monotherapy were retrospectively analyzed. Of the 305 patients, 93 received hormonal therapy for a median of 6 months (range, 1-33 months) before implantation. The prescribed dose to the prostate plus 3- to 5-mm margin was set at 145 Gy. The mean dose to 90% of the prostate volume at 1 month (D90) and the prostate volume receiving at least 100% dose at 1 month (V100) were 173.4 Gy and 95.8%, respectively. The median follow-up was 66 months (range, 12-94 months). The 5-year biochemical non-evidence of disease rate was 95.5% (low-risk, 94.2%; intermediate-risk, 97.3%). The 5-year freedom from clinical failure rate was 98.9% (low-risk, 98.9%; intermediate-risk, 99.2%).The initial prostate-specific antigen level was identified as a significant predictive factor for biochemical recurrence (P = 0.029). The late Grade 3 genitourinary toxicity rate was 2.0%. No patients displayed late gastrointestinal toxicity of Grade 3 or worse. Monotherapy with [sup.125]I showed excellent outcomes with limited morbidity for Japanese men with low- and intermediate-risk prostate cancer after 5 years of follow-up. Keywords: prostate cancer, brachytherapy, low dose rate, [sup.125]I, monotherapy