Van den Brenk
The addition of hyperbaric oxygen during irradiation of carcinomas of the head and neck and urinary bladder did not result in statistically significant improvement in survival at six months.
| Clinical Bottom Line: |
| 1. A trend to improved survival at six months with tumours of the head and neck treated with hyperbaric oxygen while being irradiated. 2. Improved survival at four months with tumours of the urinary bladder treated with hyperbaric oxygen during irradiation. |
Appraised by: Mike Bennett, Dept. of Diving and Hyperbaric Medicine, Prince of Wales Hospital Sydney; Monday, 29 March 1999
Clinical Scenario: A patient with a squamous cell tumour of the tonsillar fossa presented for radiotherapy. Three-part Question: For patients with tumours of either the head and neck or bladder, does the addition of hyperbaric oxygen to the usual radiotherapy regimen result in any improvement in survival? Search Terms: Carcinoma/ head and neck, bladder
The Study: Non-blinded pseudo-randomised controlled trial without intention-to-treat. Patients with carcinoma of the head and neck or bladder, without metastases and with prognosis sufficient to expect survival for long enough to assess tumour response. Control group 1. Head and neck. (N = 12; 11 analysed): A 4 dose fractionation regimen of 775 rads/dose as an outpatient. 2. Bladder. (N = 8; 8 analysed): A 6 dose fractionation regimen of 550 rads/fraction as an outpatient. Experimental group 1. Head and neck. (N = 17; 15 analysed): A 4 dose schedule as above but with a dose of 725 rads/fraction while breathing 100% oxygen at 4ATA for a total chamber time of 44 minutes. Patients largely treated in hospital. 2. Bladder. (N = 8; 8 analysed): A 6 fraction dose schedule as above but with a dose of 500 rads/fraction while breathing oxygen as for group one.
The Evidence:
Head and Neck
| Outcome | Time to Outcome | Air group | HBO group | Relative risk reduction | Absolute risk reduction | NNT |
| Persistent tumour | 6 months | 0.833 | 0.471 | 43% | 0.36 | 3 |
| 95% CI: | 5% to 82% | 0.04 to 0.68 | 1 to 22 | |||
| Death | 6 months | 0.36 | 0.2 | 44% | 0.16 | -6 |
| 95% CI: | -48% to 100% | -0.17 to 0.49 | NNT5 to INF NNH2 to INF |
Bladder
| Outcome | Time to Outcome | Air group | HBO group | Relative risk reduction | Absolute risk reduction | NNT |
| Death | 4 months | 0.62 | 0.12 | 81% | 0.5 | 2 |
| 95% CI: | 30% to 100% | 0.19 to 0.82 | 2 to 6 |
Comments: 1. Small studies with presumed low power to detect a clinically useful improvement in the survival rate. 2. Short term figures only given and bladder tumour survival is preliminary data only. 3. Higher dose hyperbaric oxygen and lower number of fractions of radiotherapy than most later studies. 4. Relevance to treatment today is limited.
Expiry date: January 2004 References: 1. Van Den Brenk HA. Hyperbaric oxygen in radiation therapy. An investigation of dose-effect relationships in tumour response and tissue damage. American Journal of Roetgenology 1968; 102:8-26.
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