Preventive cranial irradiation in the treatment of acute lymphocytic leukemia in children.

From April 1971 to September 1977, 94 children with acute lymphocytic leukemia, in whom a complete clinical and hematologic remission had been obtained received preventive cranial irradiation at the University Clinic for Radiotherapy of Vienna. So far, only in 2 of the 94 patients an initial meningeal relapse occurred. After a minimum follow-up time of 3 years, the rate of primary CNS relapse is 8%. The combination of cranial irradiation and methotrexate intrathecally, beginning currently in the first month of the complete remission, seems to be the most effective and least hazardous regimen to prevent meningeal and CNS leukemia.