title: Proton beam therapy for pediatric malignancies: a retrospective observational multicenter study in Japan.
abstract: Recent progress in the treatment for pediatric malignancies using a combination of surgery, chemotherapy, and radiotherapy has improved survival. However, late toxicities of radiotherapy are a concern in long-term survivors. A recent study suggested reduced secondary cancer and other late toxicities after proton beam therapy (PBT) due to dosimetric advantages. In this study, we evaluated the safety and efficacy of PBT for pediatric patients treated in Japan. A retrospective observational study in pediatric patients who received PBT was performed. All patients aged <20 years old who underwent PBT from January 1983 to August 2014 at four sites in Japan were enrolled in the study. There were 343 patients in the study. The median follow-up periods were 22.6 months (0.4-374.3 months) for all patients and 30.6 months (0.6-374.3 months) for survivors. The estimated 1-, 3-, 5-, and 10-year survival rates were 82.7% (95% CI: 78.5-87.0%), 67.4% (61.7-73.2%), 61.4% (54.8-67.9%), and 58.7% (51.5-65.9%), respectively. Fifty-two events of toxicity ≥ grade 2 occurred in 43 patients. Grade 4 toxicities of myelitis, visual loss (two cases), cerebral vascular disease, and tissue necrosis occurred in five patients. This study provides preliminary results for PBT in pediatric patients in Japan. More experience and follow-up with this technique are required to establish the efficacy of PBT in this patient population.
authors.affiliation: Department of Radiation Oncology, University of Tsukuba, Tsukuba, Ibaraki, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Mizumoto
authors.affiliation: Division of Proton Therapy, Shizuoka Cancer Center Hospital, Nagaizumi, Shizuoka, Japan.
authors.forename: Shigeyuki
authors.initials: S
authors.lastname: Murayama
authors.affiliation: Division of Radiation Oncology and Particle Therapy, National Cancer Center Hospital East, Kashiwa, Chiba, Japan.
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Akimoto
authors.affiliation: Department of Radiology, Hyogo Ion Beam Medical Center, Tatsuno, Hyogo, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Demizu
authors.affiliation: Department of Child Health, University of Tsukuba, Tsukuba, Ibaraki, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Fukushima
authors.affiliation: Division of Pediatrics, Shizuoka Cancer Center Hospital, Nagaizumi, Shizuoka, Japan.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Ishida
authors.affiliation: Department of Radiation Oncology, University of Tsukuba, Tsukuba, Ibaraki, Japan.
authors.forename: Yoshiko
authors.initials: Y
authors.lastname: Oshiro
authors.affiliation: Department of Radiation Oncology, University of Tsukuba, Tsukuba, Ibaraki, Japan.
authors.forename: Haruko
authors.initials: H
authors.lastname: Numajiri
authors.affiliation: Department of Radiology, National Center for Child Health and Development, Tokyo, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Fuji
authors.affiliation: Department of Radiation Oncology, University of Tsukuba, Tsukuba, Ibaraki, Japan.
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Okumura
authors.affiliation: Department of Radiation Oncology, Hokkaido University Hospital, Sapporo, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Shirato
authors.affiliation: Department of Radiation Oncology, University of Tsukuba, Tsukuba, Ibaraki, Japan.
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Sakurai
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D003131:Combined Modality Therapy; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007564:Japan; D008297:Male; D009369:Neoplasms / Q000175:diagnosis / Q000401:mortality / Q000532:radiotherapy*; D061766:Proton Therapy / Q000009:adverse effects / Q000379:methods; D011879:Radiotherapy Dosage; D012189:Retrospective Studies; D016019:Survival Analysis; D016896:Treatment Outcome; D055815:Young Adult
keywords: Observational study; PBT; pediatric; proton beam therapy; radiotherapy