Chang
Hyperbaric oxygenation during radiotherapy for advanced carcinomas of the oropharynx did not result in improved survival or local tumour control.
| Clinical Bottom Line: |
| 1. There was no evidence of improved survival or tumour clearance with the addition of hyperbaric oxygen, although there were trends in this direction. |
Appraised by: Mike Bennett, Dept. of Diving and Hyperbaric Medicine, Prince of Wales Hospital Sydney; Friday, 9 April 1999
Clinical Scenario: A patient presented with an advanced oropharyngeal carcinoma for radiotherapy. We wondered if there was any purpose in using adjunctive hyperbaric oxygen. Three-part Question: In patients with advanced oropharyngeal carcinoma having radiotherapy, does irradiation while breathing hyperbaric oxygen, compared to irradiation in air, result in any improvement in local control or survival? Search Terms: head and neck cancer
The Study: Non-blinded randomised controlled trial with intention-to-treat. Patients with carcinoma of the head and neck greater than 4cm with limited extension to adjacent structures (T3 and T4). Control group (N = 25; 25 analysed): Two controls. One group had radiotherapy in air on a conventional fractionation scheme of 6,000 rads over 30 treatments in 6 weeks, while the other had 4,200 rads over 7 treatments in 3.5 weeks. Experimental group (N = 26; 26 analysed): Irradiation while breathing oxygen 100% at 3ATA on a scheme of 3,600 rads over 6 treatments in 3 weeks.
The Evidence:
| Outcome | Time to Outcome | Air groups | HBO group | Relative risk reduction | Absolute risk reduction | NNT |
| Death | 5 years | 0.76 | 0.62 | 18% | 0.14 | 7 |
| 95% CI: | -15% to 51% | -0.11 to 0.39 | NNT3 to INF NNH=9 to INF | |||
| Local area not cleared | 6 months | 0.52 | 0.31 | 40% | 0.21 | 5 |
| 95% CI: | -10% to 91% | -0.05 to 0.47 | NNT2 to INF NNH=18 to INF | |||
| Lymph nodes positive | 6 months | 0.72 | 0.62 | 14% | -0.10 | 10 |
| 95% CI: | -22% to 50% | -0.16 to 0.36 | NNT3 to INF NNH=6 to INF |
Comments: 1. No blinding and two control groups make interpretation difficult. There was no trend to different outcomes in the two control groups. 2. The trend to improved control and survival was not statistically significant in this small trial. 3. The relevance for treatment today is unclear.
Expiry date:January 2020
References: 1. Chang CH, Conley JJ, Herbert C. Radiotherapy of advanced carcinoma of the oropharyngeal region under hyperbaric oxygenation. An interim report. American Journal of Roetgenology 1973; 117:509-515
