Hyperbaric oxygenation for tumour sensitisation to radiotherapy
Abstract
Background
Cancer is a common disease and radiotherapy is one well‐established treatment for some solid tumours. Hyperbaric oxygenation (HBO) may improve the ability of radiotherapy to kill hypoxic cancer cells, so the administration of radiotherapy while breathing HBO may result in a reduction in mortality and recurrence.
Objectives
To assess the benefits and harms of radiotherapy while breathing HBO.
Search methods
In September 2008 we searched The Cochrane Central Register of Controlled Trials (CENTRAL), (The Cochrane Library, Issue 3), MEDLINE, EMBASE, CINAHL, DORCTHIM and reference lists of articles.
Selection criteria
Randomised and quasi‐randomised studies comparing the outcome of malignant tumours following radiation therapy while breathing HBO versus air.
Data collection and analysis
Three review authors independently evaluated the quality of the relevant trials and extracted the data from the included trials.
Main results
Nineteen trials contributed to this review (2286 patients: 1103 allocated to HBO and 1153 control). With HBO, there was a reduction in mortality for head and neck cancers at both one year and five years after therapy (Relative risk (RR) 0.83, P = 0.03, number needed to treat (NNT) = 11 and RR 0.82, P = 0.03, NNT = 5 respectively), as well as improved local tumour control at three months (RR with HBOT 0.58, P = 0.006, NNT = 7). The effect of HBO varied with different fractionation schemes. Local tumour recurrence was less likely with HBO at one year (head and neck, RR 0.66, P < 0.0001, NNT = 5), two years (uterine cervix RR 0.60, P = 0.04, NNT = 5) and five years (head and neck (RR 0.77, P = 0.01). Any advantage is achieved at the cost of some adverse effects. There was a significant increase in the rate of both severe radiation tissue injury (RR 2.35, P < 0.0001, (number needed to harm (NNH) = 8) and the chance of seizures during therapy (RR 6.76, P = 0.03, NNH 22) with HBO.
Authors' conclusions
There is some evidence that HBO improves local tumour control and mortality for cancers of the head and neck, and local tumour recurrence in cancers of the head and neck, and uterine cervix. These benefits may only occur with unusual fractionation schemes. HBO is associated with significant adverse effects including oxygen toxic seizures and severe tissue radiation injury. The methodological and reporting inadequacies of the studies included demand a cautious interpretation. More research is needed for head and neck cancer, but is probably not justified for bladder cancer. There is little evidence available concerning malignancies at other anatomical sites on which to base a recommendation.
PICOs
Plain language summary
High pressure oxygen breathing during radiotherapy for cancer treatment
Breathing oxygen while at raised pressure in a closed chamber (hyperbaric oxygen or HBO) may increase the effectiveness of Breathing HBO involves enclosing patients in a specially designed chamber and it is sometimes used to increase the effect of radiotherapy and thus improve both mortality and tumour regrowth. We found some evidence that people with head and neck cancer are less likely to die within five years if they are treated this way, and evidence that re‐growth of tumour at the original site is less likely for head and neck, and cervical cancer. However, HBO may only be effective when radiotherapy is given in an unusually small number of sessions, each with a relatively high dose. HBO does not appear to work for other cancers studied. Our conclusions are based on 19 randomised trials with over 2000 patients.
