High-energy protons in the postoperative treatment of malignant glioma

Fractionated irradiation with high-energy protons was given postoperatively to seven patients with malignant glioma. In four cases in which detailed microscopic examinations were performed, radiation induced tumour necrosis was evident but in all four cases viable tumour cells were also observed. No abnormalities that could be attributed to radiation were observed in brain tissue free from tumour. The therapeutic results were comparable to the results achieved by other modern therapies. The results support the view that the RBE of high-energy protons is similar to that for 60Co radiation. It is suggested that a larger radiation dose, delivered by a homogeneous, well-defined proton field could possibly result in an improved therapeutic result without undue risk of injury to normal brain tissue.