Central Nervous System Therapy and Combination Chemotherapy of Childhood Lymphocytic Leukemia

In earlier combination chemotherapy regimens for childhood acute lymphocytic leukemia, nervous system leukemia terminated complete remission in over half the patients in a median time of 11 months. In the present study, cranial radiation (2400 R, ⁶⁰Co) and intrathecal methotrexate given early in remission were added to combination chemotherapy in an attempt to prevent or delay central nervous system relapse and termination of complete remission. Of 35 consecutive children with previously untreated acute lymphocytic leukemia, 20 of 30 who attained remission and received all initial phases of therapy have been in continuous complete remission for 23 to 30 months. Complete remission was terminated by nervous system relapse in three patients and by hematological relapse in five. Two patients died in complete remission of viral infections and others experienced reversible drug toxicity. We conclude that this combined therapy reduces the incidence of nervous system relapse in the first 2 years and prolongs complete remission.