title: Carbon Ion Radiation Therapy for Unresectable Sacral Chordoma: An Analysis of 188 Cases.
abstract: OBJECTIVE
  To evaluate the results of carbon ion radiation therapy administered to 188 patients with unresectable primary sacral chordomas.
  
  
  METHODS
  One hundred eighty-eight patients were treated with carbon ion radiation therapy at a single institute between 1996 and 2013 and retrospectively analyzed. The median age was 66 years. The highest proximal invasion reached past S2 level in 137 patients. The median clinical target volume was 345 cm(3). One hundred six patients received 67.2 gray equivalents (GyE)/16 fractions (fr), 74 patients received 70.4 GyE/16 fr, 7 patients received 73.6 GyE/16 fr, and 1 patient received 64.0 GyE/16 fr.
  
  
  RESULTS
  The median follow-up period was 62 months (range, 6.8-147.5 months). Seventy percent of patients were followed for 5 years or until death. The 5-year local control, overall survival, and disease-free survival rates were 77.2%, 81.1%, and 50.3%, respectively. Forty-one patients had a local recurrence. Sex, tumor volume, level of proximal invasion, and irradiated dose were unrelated to local control. There was grade 3 toxicity of the peripheral nerves in 6 patients and grade 4 toxicity of the skin in 2 patients. Ambulation remained in 97% of patients.
  
  
  CONCLUSIONS
  Carbon ion radiation therapy was safe and effective for unresectable chordoma and provided good local control and survival while preserving ambulation.
authors.affiliation: Research Center Hospital for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba, Japan. Electronic address: r_imai@nirs.go.jp.
authors.forename: Reiko
authors.initials: R
authors.lastname: Imai
authors.affiliation: Research Center Hospital for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba, Japan.
authors.forename: Tadashi
authors.initials: T
authors.lastname: Kamada
authors.affiliation: Department of Orthopedic Surgery, Osaka Medical Center for Cancer and Cardiovascular Diseases, Osaka, Japan.
authors.forename: Nobuhito
authors.initials: N
authors.lastname: Araki
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002244:Carbon / Q000627:therapeutic use; D002817:Chordoma / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy*; D005260:Female; D005500:Follow-Up Studies; D063193:Heavy Ion Radiotherapy / Q000009:adverse effects / Q000379:methods*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local; D011879:Radiotherapy Dosage; D012189:Retrospective Studies; D012447:Sacrum; D013125:Spinal Neoplasms / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy*; D015996:Survival Rate; D013997:Time Factors; D047368:Tumor Burden; D016138:Walking
chemical_list: D002244:Carbon