Radiotherapy of intracranial astrocytomas: analysis of 417 cases treated from 1960 through 1969

In a review of 417 intracranial astrocytomas treated radiotherapeutically at the Mayo Clinic from 1960 through 1969, the well-known correlation of tumor grade with survival was verified. Totally unexpected was the finding that age was fully as important a discriminant as tumor grade. Another unexpected finding was that patients treated with biopsy only followed by radiation therapy did as well as or slightly better than those subjected to resection followed by postoperative radiotherapy. We could not verify the importance to survival of either large dose or large volume radiotherapy, which has been emphasized by some. Patients receiving less than 1400 rets did just as well as or slightly better than those receiving more than 1400 rets. With low grade astrocytomas, survival beyond 4 years was significantly worse (higher death rates) in the group receiving more than 1400 rets. This suggested the possibility of radiation damage with delayed manifestations. We also could not verify an increased effectiveness for the generally accepted use of total brain irradiation for high grade gliomas.