title: Long-term follow-up after proton beam therapy for pediatric tumors: a Japanese national survey.
abstract: Proton beam therapy (PBT) is a potential new alternative to treatment with photon radiotherapy that may reduce the risk of late toxicity and secondary cancer, especially for pediatric tumors. The goal of this study was to evaluate the long-term benefits of PBT in cancer survivors. A retrospective observational study of pediatric patients who received PBT was performed at four institutions in Japan. Of 343 patients, 62 were followed up for 5 or more years. These patients included 40 males and 22 females, and had a median age of 10 years (range: 0-19 years) at the time of treatment. The irradiation dose ranged from 10.8 to 81.2 GyE (median: 50.4 GyE). The median follow-up period was 8.1 years (5.0-31.2 years). The 5-, 10- and 20-year rates for grade 2 or higher late toxicities were 18%, 35% and 45%, respectively, and those for grade 3 or higher late toxicities were 6%, 17% and 17% respectively. Univariate analysis showed that the irradiated site (head and neck, brain) was significantly associated with late toxicities. No malignant secondary tumors occurred within the irradiated field. The 10- and 20-year cumulative rates for all secondary tumors, malignant secondary tumors, and malignant nonhematologic secondary tumors were 8% and 16%, 5% and 13%, and 3% and 11%, respectively. Our data indicate that PBT has the potential to reduce the risk of late mortality and secondary malignancy. Longer follow-up is needed to confirm the benefits of PBT for pediatric tumors.
authors.affiliation: Department of Radiation Oncology, University of Tsukuba, Tsukuba, Japan.
authors.forename: Masashi
authors.identifier: http://orcid.org/0000-0001-7837-1301
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.identifier: http://orcid.org/0000-0002-4465-4300
authors.initials: Y
authors.lastname: Demizu
authors.affiliation: Department of Child Health, University of Tsukuba, Tsukuba, 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, Japan.
authors.forename: Yoshiko
authors.initials: Y
authors.lastname: Oshiro
authors.affiliation: Department of Radiation Oncology, University of Tsukuba, Tsukuba, Japan.
authors.forename: Haruko
authors.initials: H
authors.lastname: Numajiri
authors.affiliation: 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, 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, Japan.
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Sakurai
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007223:Infant; D007564:Japan / Q000453:epidemiology; D008297:Male; D009369:Neoplasms / Q000532:radiotherapy*; D009381:Neoplasms, Radiation-Induced / Q000453:epidemiology*; D061766:Proton Therapy / Q000009:adverse effects*; D011879:Radiotherapy Dosage; D012189:Retrospective Studies; D011795:Surveys and Questionnaires; D055815:Young Adult
keywords: Late toxicity; pediatrics; proton; radiotherapy; secondary cancer