A protocol for the prophylaxis of CNS leukemia was devised involving intermittent low‐dosage radiation of the craniospinal axis combined with single intrathecal injections of MTX. The retionale for this protocol was the timing of first CNS relapses in patients not receiving prophylaxis which suggests that leukemic colonization of the CNS is not restricted to the initial stage of the disease and that periodic measures might be advantageous. The low dosage of radiation was chosen because it is well tolerated and has been found temporarily effective in overt CNS relapse. The two series of patients were comparable as to various parameters. Results after three years of observation were comparable to those obtained by others with a single initial course of high‐dose radiation, with an expected 50% uninterrupted complete 5‐year remission. On the basis of 30 months follow up in 26 patients, the therapy is well tolerated. An increase in morbidity due to infections in remission was not associated with a higher mortality.
- acute childhood leukemia
- fractional low dose radiation
- intermittent CNS
- intrathecal methotrexate