A multi-institutional analysis of prospective studies of carbon ion radiotherapy for prostate cancer: A report from the Japan Carbon ion Radiation Oncology Study Group (J-CROS).

A multi-institutional observational study (J-CROS1501PR) has been carried out to analyze outcomes of carbon-ion radiotherapy (CIRT) for patients with prostate cancer.

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.

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%.

Favorable overall outcomes of CIRT for prostate cancer were suggested by the analysis of the first multi-institutional data.

Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology. 2016 Nov 08 [Epub ahead of print]

Takuma Nomiya, Hiroshi Tsuji, Hidemasa Kawamura, Tatsuya Ohno, Shingo Toyama, Yoshiyuki Shioyama, Yuko Nakayama, Kenji Nemoto, Hirohiko Tsujii, Tadashi Kamada

Department of Radiation Oncology, Kanagawa Cancer Center, Japan. Electronic address: ., National Institute of Radiological Sciences, Chiba, Japan., Gunma University Heavy Ion Medical Center, Japan., Ion Beam Therapy Center, SAGA-HIMAT Foundation, Japan., Department of Radiation Oncology, Kanagawa Cancer Center, Japan., Department of Radiation Oncology, Yamagata University Hospital, Japan.