Predicting the severity of acute urinary toxicity after brachytherapy with iodine-125 for localized prostate cancer.

Prostate cancer is one of the common cancers in the world. In Japan, prostate brachytherapy (PB) with iodine-125 has become a treatment option for localized prostate cancer since 2003. Nevertheless, severe acute urinary toxicity (AUT) remains as one of the intractable side effects. We assessed AUT and the changes in international prostate symptom score (IPSS) before and after PB for localized prostate cancer. IPSS is a questionnaire tool for tracking the subjective urinary symptoms. Between 2006 and 2009, 104 eligible patients underwent PB with iodine-125 were analyzed. AUT was graded with the radiation therapy oncology group (RTOG) scale. Eligible patients filled out IPSS questionnaires before and after PB. Clinical and treatment-related factors were examined for correlation with the severity of AUT and the interval to IPSS resolution. AUT of RTOG Grade 0 (no changes) and Grade 2 was detected in one and 96 patients, respectively, whereas seven patients (6.7%) experienced AUT of Grade 3. Thus, the incidence of severe AUT (Grade 3) after PB was low. A greater number of needles (p = 0.012) were associated with AUT of RTOG Grade 3 on the univariate analysis. The median interval to IPSS resolution was 6 months (7 ± 6 months). Greater post-implant maximal IPSS (p < 0.001) was associated with slower IPSS resolution, whereas higher pre-implant IPSS (p < 0.001) was associated with faster IPSS resolution on the multivariate analysis. In conclusion, reducing the number of needles in PB may be helpful for decreasing the rate of severe AUT.