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Background and Purpose: A multi-institutional observational study (J-CROS1501PR) has been carried out to analyze outcomes of carbon-ion radiotherapy (CIRT) for patients with prostate cancer., Patients and Methods: Data of the patients enrolled in prospective studies of following 3 CIRT institutions were analyzed: National Institute of Radiological Sciences (NIRS; Chiba, Japan), Gunma University Heavy Ion Medical Center (GHMC; Gunma, Japan), and Ion Beam Therapy Center, SAGA HIMAT Foundation (HIMAT; Saga, Japan). Endpoints of the clinical trial are biochemical recurrence-free survival (bRFS), overall survival (OS), cause-specific survival (CSS), local control rate (LCR), and acute/late adverse effects., Results: A total of 2157 patients' data were collected from NIRS (n=1432), GHMC (n=515), and HIMAT (n=210). The number of patients in low-risk, intermediate-risk, and high-risk groups was 263 (12%), 679 (31%), and 1215 (56%), respectively. The five-year bRFS in low-risk, intermediate-risk, and high-risk patients was 92%, 89%, and 92%, respectively. The five-year CSS in low-risk, intermediate-risk, and high-risk patients was 100%, 100%, and 99%, respectively. The incidence of grade 2 late GU/GI toxicities was 4.6% and 0.4%, respectively, and the incidence of ⩾G3 toxicities were 0%., Conclusions: Favorable overall outcomes of CIRT for prostate cancer were suggested by the analysis of the first multi-institutional data., (Copyright © 2016 The Authors. Published by Elsevier Ireland Ltd.. All rights reserved.)

Recent advances in external beam radiotherapy have allowed us to deliver higher doses to the tumors while decreasing doses to the surrounding tissues. Dose escalation using high-precision radiotherapy has improved the treatment outcomes of prostate cancer. Intensity-modulated radiation therapy has been widely used throughout the world as the most advanced form of photon radiotherapy. In contrast, particle radiotherapy has also been under development, and has been used as an effective and non-invasive radiation modality for prostate and other cancers. Among the particles used in such treatments, protons and carbon ions have the physical advantage that the dose can be focused on the tumor with only minimal exposure of the surrounding normal tissues. Furthermore, carbon ions also have radiobiological advantages that include higher killing effects on intrinsic radio-resistant tumors, hypoxic tumor cells and tumor cells in the G0 or S phase. However, the degree of clinical benefit derived from these theoretical advantages in the treatment of prostate cancer has not been adequately determined. The present article reviews the available literature on the use of particle radiotherapy for prostate cancer as well as the literature on the physical and radiobiological properties of this treatment, and discusses the role and the relative merits of particle radiotherapy compared with current photon-based radiotherapy, with a focus on proton beam therapy and carbon ion radiotherapy., (© 2014 The Japanese Urological Association.)

The prognosis of high-risk prostate cancer is poor with a high mortality rate. The Radiation Therapy Oncology Group (RTOG) has performed dose-escalation studies of external beam radiation therapy (EBRT) and has developed high-precision radiation therapy (RT) methods such as intensity-modulated RT, carbon ion therapy, and proton beam therapy. High-dose rate brachytherapy (HDR-BT) is also studied as an option for high-risk prostate cancer treatment. Past clinical trials have suggested that the local control rate of high-risk prostate cancer improves with total EBRT dose, even for doses > 70 Gy. Several randomized controlled trials, including RTOG 94-06, have shown significantly better prognoses with higher doses (> 75 Gy) than with lower doses (< 70 Gy). A proton beam therapy trial (PROG 95-09) also showed similar results. A phase II clinical trial (National Institute for Radiological Sciences, Japan; trial 9904) showed that carbon ion therapy resulted in very good biochemical recurrence-free survival rates among high-risk prostate cancer patients, demonstrating particle therapy to be a valid treatment option. RTOG 86-10 showed that short-term neo-adjuvant hormonal therapy (HT) was inadequate for high-risk prostate cancer but effective for intermediate-risk prostate cancer, whereas RTOG 92-02 and the European Organisation for Research and Treatment of Cancer (EORTC) 22863 showed significant improvements in the prognosis of high-risk groups receiving long-term (> 2 years) HT combined with definitive RT. Further studies are warranted to elucidate optimal irradiation doses, HT treatment durations, and combination therapy schedules., (Copyright © 2013 Elsevier Ltd. All rights reserved.)