Treatment of supratentorial high grade gliomas with split course high fractional dose postoperative radiotherapy

Abstract

Ninety-two patients with malignant supratentorial gliomas diagnosed from 1977 to 1983 received split course external beam radiotherapy. The initial course of radiation consisted of 3000 cGy whole brain in ten fractions 5 days a week. After a 2-week rest, treatment was continued to a portal restricted to the computerized tomography scan demonstrated abnormality plus a margin for an additional 2100 cGy (total 5100 cGy/17 fx/36 days). The optic chiasm and hypothalamus were excluded from the high dose region. Following review of all pathologic specimens, three patients with grade II glioma, three lacking histologic confirmation, two unbiopsied and eleven not receiving the prescribed treatment were excluded from the survival analysis. No patients were lost to follow-up. Surviving patients were followed 85 months (median); range 68–125 months. All remaining patients were followed until death. The median actuarial survival for 73 grade III and IV patients was 12.5 months. The 5-year actuarial survival was 10%. The median survival for 54 grade IV patients was 10 months. The 5-year survival was 4%. For 19 grade III patients the median survival was 22.5 months. The 5-year survival was 26%. There was one long-term grade IV survivor (68 mos.) and four long-term grade III survivors (76, 85, 108, 125 mos). No patient developed optic nerve or chiasm injury. One patient, an 85 months survivor, had biopsy documented radionecrosis and hemiparesis. The incidence of necrosis among 62 patients alive 6 months or more (and therefore at risk of brain necrosis) is 1 62 (2%). The incidence among survivors is 1 5 . The nominal standard dose for this regimen is 1749 ret. The predictive value of the “nominal standard dose” and “equivalent dose” formulae for brain necrosis is explored. We conclude (a) that this regimen provides a survival probability equivalent to conventional treatment for grade III and IV supratentorial gliomas, (b) that neither the equivalent nor nominal standard doses predicted the incidence of brain necrosis, (c) that the time dose schedule is well tolerated and has an acceptable risk-benefit ratio, (d) that its advantage to the patient is decreased time requirement and cost.