Malignant brain tumor treatments and hyperbaric oxygenation

Malignant brain tumor treatment and hyperbaric oxygenation: Combined hyperbaric oxygenation (HBO) therapy and radiation therapy of malignant gliomas is reviewed. Malignant glioma tissue is hypoxic, and the efficacy of radiation therapy is increased by raising the oxygen density in glioma tissue. Residual tumor was reduced by a radiation dose of approximately 40 Gy in many cases when radiation therapy was begun within 15 minutes after HBO. In the experiment in animal models with different hypoxic fractions (HFs) of cells (SCCVII and 9L gliosarcoma), the tumor reduction effect was more significant in the SCCVII model, which has a higher HF. When the SCCVII model was irradiated within 30 minutes after HBO, the improvement effect was more significant (1.60-1.78 times) than by irradiation alone. HBO was effective in the treatment of radionecrosis of the brain. However, there were some cases in which radionecrosis progressed when the HBO treatments were discontinued, and the optimal duration of HBO treatment should be determined. It is difficult to differentiate between radionecrosis and tumor recurrence after radiosurgery of a malignant intracranial tumor. When no lesion reduction is observed in response to HBO treatment and steroid administration for about one month, the lesion is concluded to be a recurrence of the tumor, and additional irradiation should be performed. HBO treatment in combination with chemotherapy is also discussed. (K.H.)