Radiation therapy with uneven fractionation for malignant gliomas.

From 1989 to 1995, we administered a combination of large and small fraction doses (UFX, uneven fractionation) for patients with malignant gliomas. In this study, we compared the treatment outcomes of radiation therapy by uneven fractionation to that of historical control which was treated with radiation therapy by conventional fractionation (CFX). The pathologic classification was anaplastic astrocytoma (AA) in 120 and glioblastoma multiforme (GBM) in 64 patients. Of the 184 patients, 89 patients received a conventional fractionation schedule (CFX) of radiation (2 Gy/fraction, 5 times/week; total, 60 Gy/6 weeks). The other 95 patients received an uneven fractionation schedule (UFX) of radiation (5 Gy on Monday, 1 Gy from Tuesday through Friday; total, 63 Gy/7 weeks). The one-, two-, and five-year survival rates of the AA patients were 74%, 55%, and 30%, respectively. The five-year survival rates of AA patients who received CFX and UFX schedule of radiation were 24% and 38%, respectively. In the GBM patients, the five-year survival rates were 12% in patients who received CFX and 11% in patients who received UFX. UFX seemed to be more effective than CFX for treating AA patients. In multivariate analysis using the Cox regression analysis, which included various patients and treatment characteristics, age, histology and extent of surgery were the significant prognostic factors. In conclusion, UFX is an promising fractionation method for AA patients but not for GBM patients.