Temozolomide is currently being used for aggressive brain tumors, among other cancers. The effectiveness of this treatment is reduced with tumor hypoxia (low oxygen levels). Hyperbaric oxygen therapy was shown in this study to reduce tumor hypoxia and thus help to increase the effectiveness of Temozolomide against the glioma, producing a much more powerful anti-tumor activity. This research is consistent with many recent studies showing the added effectiveness of hyperbaric oxygen therapy with conventional therapies like chemotherapy, in helping to increase the effectiveness of these therapies <view study>