A Japanese multi-institutional phase II study of moderate hypofractionated intensity-modulated radiotherapy with image-guided technique for prostate cancer

Abstract

Background Although moderate hypofractionated radiotherapy were one of standard regimens for localized prostate cancer, the e cacy of moderated hypofractionated regimens has not been well validated in Asian countries. The aim of this multi-institutional phase II study was to con rm the safety and the potential e cacy of moderately hypofractionated intensity-modulated radiotherapy (IMRT) with prostate-based image-guidance for Japanese patients.Methods Patients with low-or intermediate-risk localized prostate cancer were eligible. Patients with a part of high risk (having only one of the following factors, cT3a, 20 < PSA ≤ 30, or GS = 8 or 9) were also included in this trial. Hypofractionated IMRT using daily image-guided technique with prostate matching was performed with a total dose of 70 Gy in 28 fractions. Neoadjuvant hormonal therapy for 4-8 months was mandatory for patients with intermediate or high-risk prostate cancer. ResultsThe number of patients with low, intermediate, and high-risk prostate cancer was 20, 80, and 34, respectively. The 5-year overall, biochemical failure-free, and clinical failure-free survival was 94.5%, 96.0%, and 99.2%, respectively. The 5-year biochemical failure-free survival for patients with low-, intermediate-, and high-risk disease was 94.1%, 97.4%, and 93.9%, respectively. The incidences of grade 2 gastrointestinal and genitourinary late toxicities at 5 years were 5.3% and 5.3%, respectively. There are no acute or late toxicities ≥ grade 3. ConclusionThe safety and e cacy of moderately hypofractionated IMRT was con rmed in this trial among Japanese patients with prostate cancer.