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.
Department of Radiation Oncology, Kanagawa Cancer Center, Japan. Electronic address: tnomiya@kcch.jp.
Takuma
T
Nomiya
National Institute of Radiological Sciences, Chiba, Japan.
Hiroshi
H
Tsuji
Gunma University Heavy Ion Medical Center, Japan.
Hidemasa
H
Kawamura
Gunma University Heavy Ion Medical Center, Japan.
Tatsuya
T
Ohno
Ion Beam Therapy Center, SAGA-HIMAT Foundation, Japan.
Shingo
S
Toyama
Ion Beam Therapy Center, SAGA-HIMAT Foundation, Japan.
Yoshiyuki
Y
Shioyama
Department of Radiation Oncology, Kanagawa Cancer Center, Japan.
Yuko
Y
Nakayama
Department of Radiation Oncology, Yamagata University Hospital, Japan.
Kenji
K
Nemoto
National Institute of Radiological Sciences, Chiba, Japan.
Hirohiko
H
Tsujii
National Institute of Radiological Sciences, Chiba, Japan.
Tadashi
T
Kamada
D000230:Adenocarcinoma / Q000532:radiotherapy*; D000368:Aged; D002244:Carbon; D063193:Heavy Ion Radiotherapy / Q000009:adverse effects / Q000379:methods*; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011471:Prostatic Neoplasms / Q000532:radiotherapy*; D018570:Risk Assessment / Q000379:methods; D016896:Treatment Outcome
D002244:Carbon
Carbon-ion radiotherapy; External beam radiotherapy; Multi-institutional analysis; Observational study; Prostate cancer