title: Efficacy and Safety of Adjuvant Proton Therapy Combined With Surgery for Chondrosarcoma of the Skull Base: A Retrospective, Population-Based Study.
abstract: OBJECTIVE
  Chondrosarcoma is a rare malignant tumor of the cartilage affecting young adults. Surgery, followed by charged-particle irradiation, is considered the reference standard for the treatment of patients with grade I to II skull base chondrosarcoma. The present study was conducted to assess the effect of the quality of surgery and radiation therapy parameters on local control (LC) and overall survival (OS).
  
  
  METHODS
  From 1996 to 2013, 159 patients (median age 40 years, range 12-83) were treated with either protons alone or a combination of protons and photons. The median total dose delivered was 70.2 Gy (relative biologic effectiveness [RBE]; range 67-71). Debulking and biopsy were performed in 133 and 13 patients, respectively.
  
  
  RESULTS
  With a median follow-up of 77 months (range 2-214), 5 tumors relapsed based on the initial gross tumor volume. The 5- and 10-year LC rates were 96.4% and 93.5%, respectively, and the 5- and 10-year OS rates were 94.9% and 87%, respectively. A total of 16 patients died (13 of intercurrent disease, 3 of disease progression). On multivariate analysis, age <40 years and primary disease status were independent favorable prognostic factors for progression-free survival and OS, and local tumor control was an independent favorable predictor of OS. In contrast, the extent of surgery, dosimetric parameters, and adjacent organs at risk were not prognostic factors for LC or OS.
  
  
  CONCLUSIONS
  Systematic high-dose postoperative proton therapy for skull base chondrosarcoma can achieve a high LC rate with a low toxicity profile. Maximal safe surgery, followed by high-dose conformal proton therapy, is therefore recommended.
authors.affiliation: Department of Radiation Oncology, Groupe Hospitalier La Pitié-Salpêtrière-Charles Foix (Assistance Publique-Hôpitaux de Paris), Paris, France; Department of Radiation Oncology, Institut Curie-Centre de protonthérapie d'Orsay (CPO), Orsay, France. Electronic address: loic.feuvret@psl.aphp.fr.
authors.forename: Loïc
authors.initials: L
authors.lastname: Feuvret
authors.affiliation: Institute of Radiation Oncology, Sapienza University, Sant'Andrea Hospital, Rome, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Bracci
authors.affiliation: Department of Radiation Oncology, Institut Curie-Centre de protonthérapie d'Orsay (CPO), Orsay, France.
authors.forename: Valentin
authors.initials: V
authors.lastname: Calugaru
authors.affiliation: Department of Radiation Oncology, Gustave Roussy, Villejuif, France.
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Bolle
authors.affiliation: Department of Radiation Oncology, Institut Curie-Centre de protonthérapie d'Orsay (CPO), Orsay, France.
authors.forename: Hamid
authors.initials: H
authors.lastname: Mammar
authors.affiliation: Department of Radiation Oncology, Institut Curie-Centre de protonthérapie d'Orsay (CPO), Orsay, France.
authors.forename: Ludovic
authors.initials: L
authors.lastname: De Marzi
authors.affiliation: Department of Neurosurgery, Hôpital Lariboisière (Assistance Publique-Hôpitaux de Paris), Paris, France.
authors.forename: Damien
authors.initials: D
authors.lastname: Bresson
authors.affiliation: Department of Radiation Oncology, Centre François Baclesse, Caen, France.
authors.forename: Jean-Louis
authors.initials: JL
authors.lastname: Habrand
authors.affiliation: Department of Radiation Oncology, Groupe Hospitalier La Pitié-Salpêtrière-Charles Foix (Assistance Publique-Hôpitaux de Paris), Paris, France.
authors.forename: Jean-Jacques
authors.initials: JJ
authors.lastname: Mazeron
authors.affiliation: Department of Radiation Oncology, Institut Curie-Centre de protonthérapie d'Orsay (CPO), Orsay, France.
authors.forename: Rémi
authors.initials: R
authors.lastname: Dendale
authors.affiliation: Department of Radiation Oncology, Centre Paul Strauss, Strasbourg, France.
authors.forename: Georges
authors.initials: G
authors.lastname: Noël
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002813:Chondrosarcoma / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D005500:Follow-Up Studies; D006801:Humans; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local; D059351:Organ Sparing Treatments; D058958:Organs at Risk; D017785:Photons / Q000627:therapeutic use; D061766:Proton Therapy / Q000009:adverse effects / Q000379:methods; D018714:Radiotherapy, Adjuvant / Q000009:adverse effects / Q000379:methods; D012062:Relative Biological Effectiveness; D012189:Retrospective Studies; D019292:Skull Base Neoplasms / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D015996:Survival Rate; D013997:Time Factors; D047368:Tumor Burden