149 children with acute lymphocytic leukemia (ALL) were admitted to a prospective therapeutic regime. Remission induction was achieved by vincristine, daunorubicine, L-asparaginase and prednisone. During consolidation the patients received three intermediate dose methotrexate (MTX) infusions over 24 hours combined with intrathecal MTX, followed by L-asparaginase. High-risk patients were treated in addition with high dose cyclophosphamide and ARA-C over 3 weeks. Standard risk patients received cranial irradiation with 18 Gy, high-risk patients with 24 Gy. Maintenance therapy was performed with 6-mercaptopurine and MTX orally. Immunologic phaenotyping revealed: c-ALL 73%, pre-T or T-ALL 15%, c/T-ALL 4% and undifferentiated leukemia (AUL) 8%. Only 1 patient was nonresponder, 7 patients died during induction therapy, 5 patients during continuous complete remission (CCR). 18 relapses occurred, 12 of which were systemic, 8 CNS and 2 testicular relapses. In the total group the 54 months probability of CCR is 0,68 +/- 0,05 (life-table-analysis), for the reduced group 0,75 +/- 0,05. In the reduced group the probability of CCR at 54 months for standard risk patients is 0,86 +/- 0,06; for high-risk patients 0,60 +/- 0,09; for patients with c-ALL 0,73 +/- 0,08; for patients with c/T-ALL 1,0 +/- 0,0; for patients with pre-T or T-ALL 0,58 +/- 0,2 and for patients with AUL 0,45 +/- 0,25. For the reduced group the CCR probability at 54 months in relation to the leukocytes (WBC) at diagnosis is in patients with WBC less than 25 X 10(3)/mm3: 0,80 +/- 0,06; for patients with WBC greater than 25 X 10(3)/mm3: 0,63 +/- 0,11.
