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Hyperbaric oxygen therapy did not improve outcome following chemotherapy for breast cancer

Clinical bottom line:
1. There were trends to lower mortality and better clinical response in the control group.

Citation:1. Heys SD, Smith IC, Ross JA, Gilbert FJ, Brooks J, Semple S, Miller ID, Hutcheon A, Sarkar T, Eremin O. A pilot study with long term follow up of hyperbaric oxygen pre-treatment in patients with locally advanced breast cancer undergoing neo-adjuvant chemotherapy. Undersea and Hyperbaric Medicine 2006; 33(1):33-43. Lead author's name: Heys SD, Department of Surgery, University of Aberdeen

Three-part Clinical Question: For patients with locally advanced breast cancer, does pre-treatment with HBOT before chemotherapy result in any improvement in mortality or tumour control? Search Terms: Hyperbaric oxygenation, chemotherapy.

The Study: Non-blinded randomised controlled trial without intention-to-treat. Study Patients: Women under 75 years with large primary breast cancer (>5cm) but no evidence of metastatic disease. Control group (N = 17; 17 analysed): Six pulses of CVAP chemotherapy every 21 days. Some adjustment of dose downwards with low white cell counts. Then surgical removal and axillary node biopsy. Experimental group (N = 15; 11 analysed): As above plus 100% oxygen at 2.4 ATA daily for 90 minutes for ten days (6 subjects) or 2.0 ATA daily for 90 minutes for ten days (9 subjects).

The Evidence:

Outcome Time to Outcome Control group rate HBOT group rate Relative risk reduction Absolute risk reduction Number needed to treat
Death Five years 0.24 0.18 23% 0.05 19
^ 95% Confidence Intervals: -107% to 100% -0.25 to 0.36 NNT 3 to INF NNH 4 to INF
Tumour response to therapy (pathological) End of treatment 0.59 0.27 54% 0.32 3
^ 95% Confidence Intervals: -6% to 100% -0.04 to 0.67 NNT 1 to INFNNH 27 to INF
Tumour response to therapy (clinical) End of treatment 0.59 0.82 -39% -0.23 -4
^ 95% Confidence Intervals: -95% to 16% -0.56 to 0.10 NNT 10 to INF NNH 2 to INF

Comments: 1. A small trial with low power to detect important differences. Not blinded. 2. The HBOT group appear to have had chemotherapy delayed for two weeks. 3. There were four withdrawals from the HBOT arm. One HBO patient died of an MI after one pulse and three others were withdrawn from treatment. They were all omitted from analysis. 3. The HBOT regimen was changed to lower pressure after the first six patients suggested poor tolerance of HBOT. 4. There was a significant reduction in tumour extravascular water with HBOT on MRI, but no indication of increased vessel density in either group. No attempt was made to show these tumours were hypoxic.

Appraised by: Mike Bennett and Aishy Ravishankar, Diving and Hyperbaric Medicine, Sydney ; Thursday, 21st August 2008Email: [| m.bennett@unsw.edu.au] Kill or Update By: May 2009

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