Outcomes of intensity-modulated radiation therapy for intermediate- or high-risk prostate cancer: a single-institutional study

Background There are few reports from Japan about the outcomes of intensity-modulated radiation therapy for localized prostate cancer. This study was aimed at assessing the efficacy and toxicity of intensity-modulated radiation therapy in patients with intermediate- or high-risk prostate cancer. Methods We conducted a review of the data, retrieved from our institutional database, of patients who had received intensity-modulated radiation therapy for localized prostate cancer at a radiation dose of 78 Gy in 39 fractions. Data of 201 patients with intermediate-risk prostate cancer and 311 patients with high-risk prostate cancer were analyzed. Results The median follow-up period after the completion of intensity-modulated radiation therapy was 100 months (range, 24-154). The rates of cause-specific survival, overall survival, metastasis-free survival and biochemical recurrence-free survival in the intermediate-risk patients were 99, 95, 95 and 94% at 5 years and 99, 91, 90 and 86% at 8 years, respectively; the corresponding rates in the high-risk patients were 100, 97, 91 and 84% at 5 years and 96, 92, 84 and 76% at 8 years, respectively. The crude incidence of late grade 2-3 genitourinary toxicity was 28.1%, and that of late grade 3 genitourinary toxicity was 2.0%. The crude incidence of late grade 2 gastrointestinal toxicity was 5.1%, and there were no cases of late grade 3 gastrointestinal toxicity. Conclusions Our data demonstrated that intensity-modulated radiation therapy is effective for patients with localized intermediate-risk or high-risk prostate cancer while having minimal toxicity. This study evaluated the efficacy and toxicity of IMRT in 512 patients with locaized prostate cancer, and we demonstrated that clinical outcomes were satisfactory.