title: A Prospective Outcomes Study of Proton Therapy for Chordomas and Chondrosarcomas of the Spine.
abstract: OBJECTIVE
  To evaluate the effectiveness of definitive or adjuvant external beam proton therapy on survival in patients with chordomas and chondrosarcomas of the spine.
  
  
  METHODS
  Between March 2007 and May 2013, 51 patients with a median age of 58 years (range, 22-83 years) with chordoma (n=34) or chondrosarcomas (n=17) of the sacrum (n=21), the cervical spine (n=20), and the thoracolumbar spine (n=10) were treated with external beam proton therapy to a median dose of 70.2 Gy(RBE) [range, 64.2-75.6 Gy(RBE)] at our institution. Distant metastases, overall survival, cause-specific survival, local control, and disease-free survival were calculated.
  
  
  RESULTS
  The mean follow-up time was 3.7 years (range, 0.3-7.7 years). Across all time points, 25 patients experienced disease recurrence: 18 local recurrences, 6 local and distant recurrences, and 1 distant metastasis. The 4-year rates of overall survival and cause-specific survival were 72%; disease-free survival was 57%, local control was 58%, and freedom from distant metastases was 86%. The median time to local progression was 1.7 years (range, 0.2-6.0 years), and the median time to distant progression was 1.6 years (range, 0.2-6.0 years). The risk factors for local recurrence were age ≤58 years (62% vs 26%; P=.04) and recurrence after prior surgery (29% vs 81%; P=.01). Secondary cancers developed in 2 patients: B-cell lymphoma 5.5 years after treatment and bladder cancer 2 years after treatment. We observed the following toxicities: sacral soft tissue necrosis requiring surgery (n=2), T1 vertebral fracture requiring fusion surgery (n=1), chronic urinary tract infections (n=1), surgery for necrotic bone cyst (n=1), and grade 2 bilateral radiation nephritis (n=1).
  
  
  CONCLUSIONS
  High-dose proton therapy controls more than half of spinal chordomas and chondrosarcomas and compares favorably with historic photon data. Local progression is the dominant mode of treatment failure and may be reduced by treating patients at the time of initial diagnosis. The impact of age is a novel finding of this study.
authors.affiliation: Department of Radiation Oncology, University of Florida College of Medicine, Jacksonville, Florida. Electronic address: dindelicato@floridaproton.org.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Indelicato
authors.affiliation: Department of Radiation Oncology, University of Florida College of Medicine, Jacksonville, Florida.
authors.forename: Ronny L
authors.initials: RL
authors.lastname: Rotondo
authors.affiliation: Department of Radiation Oncology, University of Florida College of Medicine, Jacksonville, Florida.
authors.forename: Dustin
authors.initials: D
authors.lastname: Begosh-Mayne
authors.affiliation: Department of Orthopedics and Rehabilitation, University of Florida College of Medicine, Gainesville, Florida.
authors.forename: Mark T
authors.initials: MT
authors.lastname: Scarborough
authors.affiliation: Department of Orthopedics and Rehabilitation, University of Florida College of Medicine, Gainesville, Florida.
authors.forename: C Parker
authors.initials: CP
authors.lastname: Gibbs
authors.affiliation: Department of Radiation Oncology, University of Florida College of Medicine, Jacksonville, Florida.
authors.forename: Christopher G
authors.initials: CG
authors.lastname: Morris
authors.affiliation: Department of Radiation Oncology, University of Florida College of Medicine, Jacksonville, Florida.
authors.forename: William M
authors.initials: WM
authors.lastname: Mendenhall
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D002813:Chondrosarcoma / Q000401:mortality / Q000532:radiotherapy*; D002817:Chordoma / Q000401:mortality / Q000532:radiotherapy*; D018450:Disease Progression; D018572:Disease-Free Survival; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D061766:Proton Therapy / Q000009:adverse effects / Q000379:methods* / Q000401:mortality; D011879:Radiotherapy Dosage; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods; D012062:Relative Biological Effectiveness; D012307:Risk Factors; D013125:Spinal Neoplasms / Q000401:mortality / Q000532:radiotherapy*; D013997:Time Factors; D016896:Treatment Outcome