title: Radiotherapy alone or combined with carbogen breathing for squamous cell carcinoma of the head and neck: a prospective, randomized trial.
abstract: BACKGROUND
  The current study was performed to investigate the efficacy of carbogen (95% oxygen [O(2)] and 5% carbon dioxide [CO(2)]) breathing during definitive radiotherapy (RT) to enhance local control.
  
  
  METHODS
  Between November 1996 and November 2002, 101 patients with previously untreated T2 to T4 squamous cell carcinomas of the oropharynx, larynx, and hypopharynx were entered onto a prospective trial and randomized to receive definitive hyperfractionated RT alone or combined with carbogen breathing. Patients were stratified according to T classification and primary tumor site. Follow-up ranged from 1-91 months (median, 38 months). All living patients had follow-up for more than 2 years. Outcomes analyses were performed according to intent to treat.
  
  
  RESULTS
  Definitive RT alone was completed as planned in 50 of 51 patients (98%); 49 of the 50 patients (98%) who were randomized to receive carbogen breathing were able to complete the RT as planned. Three patients randomized to receive carbogen breathing declined carbogen. The 5-year outcomes after RT alone or combined with carbogen were as follows: local control, 83% versus 88% (P = 0.5155); locoregional control, 81% versus 83% (P = 0.7174); distant metastasis-free survival, 82% versus 86% (P = 0.5184); cause-specific survival, 73% versus 77% (P = 0.5866); and absolute survival, 53% versus 58% (P = 0.4856).
  
  
  CONCLUSIONS
  The addition of carbogen breathing to definitive RT did not appear to improve the likelihood of local control significantly. However, because of the limited size of the current study, the authors cannot definitively conclude that carbogen breathing is ineffective.
authors.affiliation: Department of Radiation Oncology, University of Florida College of Medicine, Gainesville, Florida 32610, USA. mendewil@shands.ufl.edu
authors.forename: William M
authors.initials: WM
authors.lastname: Mendenhall
authors.forename: Christopher G
authors.initials: CG
authors.lastname: Morris
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Amdur
authors.forename: Nancy P
authors.initials: NP
authors.lastname: Mendenhall
authors.forename: Dietmar W
authors.initials: DW
authors.lastname: Siemann
mesh_terms: D002245:Carbon Dioxide / Q000008:administration & dosage*; D002294:Carcinoma, Squamous Cell / Q000532:radiotherapy / Q000628:therapy*; D003131:Combined Modality Therapy; D018572:Disease-Free Survival; D006258:Head and Neck Neoplasms / Q000532:radiotherapy / Q000628:therapy*; D006801:Humans; D010100:Oxygen / Q000008:administration & dosage*; D011838:Radiation-Sensitizing Agents / Q000008:administration & dosage*; D012119:Respiration; D016019:Survival Analysis; D013997:Time Factors
chemical_list: D011838:Radiation-Sensitizing Agents; D002245:Carbon Dioxide; C011700:carbogen; D010100:Oxygen