THE RESULTS of cancer treatment by surgery, irradiation, irradiation plus surgery, chemotherapy alone or in conjunction with irradiation and surgery leave much room for improvement in cure rates. When surgery is performed after radiotherapy, healing is often delayed and surgical complications are more frequent. If radiation effects could in some way be potentiated, it might be possible to accomplish an equivalent tumoricidal effect with a smaller amount of radiation, thereby reducing post-surgical complications.
It has been shown that the radiosensitivity of living cells is in part a function of the oxygen in their environment. Gray and his co-workers1 have demonstrated that in areas of anoxia and hypoxia the effectiveness of irradiation is reduced by as much as a factor of three. In an attempt to increase the oxygenation of tumors and hence their radiosensitivity, other investigators have treated cancer patients with external irradiation while the patients were enclosed in