The purpose of this non-randomized trial was to evaluate the efficacy of ra
diotherapy combined with hyperbaric oxygen (HBO) in patients with malignant
glioma. Between 1987 and 1997, 29 patients in whom computerized tomography
(CT) or magnetic resonance imaging (MRI) scans showed post-operative resid
ual tumours were locally irradiated with nitrosourea-based chemotherapy, Tr
eatments were consecutively combined with HBO at two institutions since 199
1 and 1993. Fifteen patients were irradiated daily after HBO, and the perio
ds of time from decompression to irradiation were within 15 and 30 min in 1
1 and four patients respectively, Fourteen other patients were treated with
out HBO, Tumour responses were assessed by CT or MRI scans and survival tim
es were compared between the treated groups. In the HBO group, 11 of 15 pat
ients (73%) showed greater than or equal to 50% tumour regression. All resp
onders were irradiated within 15 min after decompression. In the non-HBO gr
oup, four of 14 patients (29%) showed tumour regression. The median surviva
ls in patients with and without HBO were 24 and 12 months, respectively and
were significantly different (P < 0.05). No serious side-effects were obse
rved in the HBO patients. In conclusion, irradiation after HBO seems to be
a useful form of treatment for malignant gliomas, but irradiation should be
administered immediately after decompression.