title: Overview of clinical experiences on carbon ion radiotherapy at NIRS.
abstract: OBJECTIVE
  Carbon ion beams provide physical and biological advantages over photons. This study summarizes the experiences of carbon ion radiotherapy at the Heavy Ion Medical Accelerator in Chiba (HIMAC) at the National Institute of Radiological Sciences.
  
  
  METHODS
  Between June 1994 and August 2003, a total of 1601 patients with various types of malignant tumors were enrolled in phase I/II dose-escalation studies and clinical phase II studies. All but malignant glioma patients received carbon ion radiotherapy alone with a fraction number and overall treatment time being fixed for each tumor site, given to one field per day and 3 or 4 days per week. In dose-escalation studies, the total dose was escalated by 5 or 10% increments to ensure a safe patient treatment and to determine appropriate dose levels.
  
  
  RESULTS
  In the initial dose-escalation studies, severe late complications of the recto-sigmoid colon and esophagus were observed in those patients who received high dose levels for prostate, uterine cervix and esophageal cancer. Such adverse effects, however, did shortly disappear as a result of determining safe dose levels and because of improvements in the irradiation method. Carbon ion radiotherapy has shown improvement of outcome for tumor entities: (a) locally advanced head and neck tumors, in particular those with non-squamous cell histology including adenocarcinoma, adenoid cystic carcinoma, and malignant melanoma; (b) early stage NSCLC and locally advanced NSCLC; (c) locally advanced bone and soft tissue sarcomas not suited for surgical resection; (d) locally advanced hepatocellular carcinomas; (e) locally advanced prostate carcinomas, in particular for high-risk patients; (f) chordoma and chondrosarcoma of the skull base and cervical spine, and (g) post-operative pelvic recurrence of rectal cancer. Treatment of malignant gliomas, pancreatic, uterine cervix, and esophageal cancer is being investigated within dose-escalation studies. There is a rationale for the use of short-course RT regimen due to the superior dose localization and the unique biological properties of high-LET beams. This has been proven in treatment of NSCLC and hepatoma, where the fraction number has been successfully reduced to 4-12 fractions delivered within 1-3 weeks. Even for other types of tumors including prostate cancer, bone/soft tissue sarcoma and head/neck tumors, it was equally possible to apply the therapy in much shorter treatment times as compared to conventional RT regimen.
  
  
  CONCLUSIONS
  Carbon ion radiotherapy, due to its physical and biologic advantages over photons, has provided improved outcome in terms of minimized toxicity and high local control rates for locally advanced tumors and pathologically non-squamous cell type of tumors. Using carbon ion radiotherapy, hypofractionated radiotherapy with application of larger doses per fraction and a reduction of overall treatment times as compared to conventional radiotherapy was enabled.
authors.affiliation: Research Center for Charged Particle Therapy National Institute of Radiological Sciences, Chiba, Japan. tsujii@nirs.go.jp
authors.forename: Hirohiko
authors.initials: H
authors.lastname: Tsujii
authors.forename: Jun-Etsu
authors.initials: JE
authors.lastname: Mizoe
authors.forename: Tadashi
authors.initials: T
authors.lastname: Kamada
authors.forename: Masayuki
authors.initials: M
authors.lastname: Baba
authors.forename: Shingo
authors.initials: S
authors.lastname: Kato
authors.forename: Hirotoshi
authors.initials: H
authors.lastname: Kato
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Tsuji
authors.forename: Shigeru
authors.initials: S
authors.lastname: Yamada
authors.forename: Shigeo
authors.initials: S
authors.lastname: Yasuda
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Ohno
authors.forename: Takeshi
authors.initials: T
authors.lastname: Yanagi
authors.forename: Azusa
authors.initials: A
authors.lastname: Hasegawa
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Sugawara
authors.forename: Hidefumi
authors.initials: H
authors.lastname: Ezawa
authors.forename: Susumu
authors.initials: S
authors.lastname: Kandatsu
authors.forename: Kyosan
authors.initials: K
authors.lastname: Yoshikawa
authors.forename: Riwa
authors.initials: R
authors.lastname: Kishimoto
authors.forename: Tadaaki
authors.initials: T
authors.lastname: Miyamoto
mesh_terms: D002244:Carbon / Q000009:adverse effects / Q000627:therapeutic use*; D019583:Dose Fractionation, Radiation; D005260:Female; D063193:Heavy Ion Radiotherapy; D020450:Heavy Ions / Q000009:adverse effects; D006801:Humans; D008297:Male; D009369:Neoplasms / Q000401:mortality / Q000532:radiotherapy*
chemical_list: D002244:Carbon