Hyperbaric Oxygen Therapy - Hyperbaric Chamber Information ...

These contrasted with the conclusions drawn from the multicentre trial by Watson et
al 109 who found that crude intervention group actuarial survival rates were marginally
better yet of borderline statistical significance (unstated statistic, p = 0.08). Various
stratification techniques uncovered highly statistically significant survival benefits for the
intervention protocol in patients with stage III disease after controlling for centre effects
(p = 0.009). The relevance of these post-hoc analyses is unknown but they are
unsatisfactory when performed without substantial protection from increasing the
probability of detecting a significant difference when none exists (Type I error).
Fletcher et al 110 and Glassburn et al, 111 failed to detect statistically significant survival
advantages between intervention and comparison groups (Table 70). The study by
Johnson and Walton 112 selectively report the experience of a subset of participants
without divulging the overall comparisons described in their methods section. The
experience of 14 subjects assigned to the comparison group are undisclosed. If
conservative assumptions are applied (ie, that all missing comparison group subjects
died), then the intervention protocol is found to be statistically significantly associated
with death over five years (p = 0.0449).
Table 70 Outcomes following treatment for cervical cancer in intervention and comparison
groups. 110,111
Outcome
Fletcher 1977
Intervention Group Comparison Group p
110
Sample size (n)
Five-year disease free survival (%)
Glassburn 1974 111
Sample size (n)
27-month disease-free survival (%)
Johnson 1974 112
Sample size (n)
Five-year disease-free survival (%)
Hyperbaric oxygen therapy 71
109
33.0
17
41.1
25
44.0
124
41.1 0.2021
23
39.1 0.8961
25
16.0 0.0308
Summary
The studies failed to provide enough evidence to come to firm conclusions about the
effectiveness of exposure to HBO in conjunction with radiotherapy for cervical cancer.
Any conclusions reached from these studies would need to take into consideration the
disparity in intervention and comparison protocols, poor methodological descriptions,
and substantial post-hoc comparisons.
Bladder cancer
Four studies were retrieved from the published literature, and judged to meet inclusion
and exclusion criteria (Table 71).