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.