Hyperbaric Oxygen Therapy - Hyperbaric Chamber Information ...

comparisons groups in the majority of studies. Furthermore, as previously stated, the
comparison groups were not exposed to any sham HBOT procedure, thus it could be
argued that the treatment regimes between intervention and comparison groups were
quite different.
Assessment of heterogeneity
Taking into consideration the wide differences in study population, study design, patient
criteria, and treatment protocols employed by the eight studies that met eligibility criteria,
the review undertook no statistical analysis of heterogeneity and made no attempt to
arrive at a statistically pooled effect estimate through meta-analysis.
Review of published clinical experience
Overall, the results of the studies were presented poorly and statistical tests used to
analyse data were rarely described. Survival rates for varying periods of time and local
tumour control were measured in all studies.
Two studies found a significantly better five-year survival rate after HBOT and
radiotherapy compared to radiotherapy alone. 100,102 However, five-year survival rates
were found not to differ in the studies of Whittle et al, 99 Chang et al, 104 and Churchill-
Davidson et al 105 Survival rates measured for shorter time periods were also found not to
differ with HBOT therapy in the remainder of the studies. 101,103,106,107 Despite the lack
of difference in survival in the studies of Whittle et al, 99 Shigamatsu et al, 106 and Henk et
al, 107 local tumour control rates were higher with HBOT treatment in those studies, as
they were in the studies of Henk et al 100 and Berry et al. 102 Sealy et al 101 found no
statistical difference in local tumour control rates between patient groups. The remaining
three studies did not state that statistical analyses were performed, but local tumour
control rates do not appear to be different between groups.
Thus, HBOT concurrent with radiotherapy has a limited effect on survival rates for
patients with head and neck cancer, while local tumour control was improved in five of
nine included studies.
Summary
The identified studies were disparate in their research designs, varied in their populations,
discrepant in their therapies, and conflicting in their outcomes and conclusions. Overall,
there is a lack of well-conducted studies to support the use of hyperbaric oxygen therapy
for head and neck cancer and there is little firm evidence of a beneficial effect..
Cervical cancer
Six published studies were collected (Table 65). The studies were published over seven
years and, except for one of the earlier studies, were primarily randomised controlled
trials. All studies were conducted in sites located in the United Kingdom or North
America. Recruitment of participants occurred over a 15 year period. Study populations
were inadequately described.
66 Hyperbaric oxygen therapy