Treatment of childhood acute lymphoblastic leukemia with protocol TCL821: a report of Taiwan Children's Cancer Study Group.

Of 110 previously untreated patients who had entered the study of protocol TCL821, 96 were evaluable. The patients were divided into a standard risk group (Group I) and a high risk group (Group II) depending on their age and leukocyte count at the time of diagnosis. Treatment consisted of a 5-week induction therapy course with prednisolone (PRED), vincristine (VCR) and adriamycin (ADM) followed by central nervous system (CNS) prophylaxis. Maintenance therapy consisted of 6-mercaptopurine (6-MP) plus methotrexate (MTX) for 3 years and 6-MP alone for another 2 years, reinforced with dexamethasone, VCR and ADM or cytosine-arabinoside (Ara-C) or cyclophosphamide (CTX) every 16 weeks for Group I and 8 weeks for Group II for 3 years. Immunologic typing was done in 74 cases which revealed 60.9% of the common acute lymphoblastic leukemia (ALL) type, 14.9% null cell type, 4.0% undifferentiated type, 4.0% Pre-B cell type, 4.0% B cell type, 10.8% Pre-T cell type and 1.4% T cell type. In Group I the complete remission rate (CR) was 100% and the continuous complete remission rate (CCR) was 72.2% with a follow-up duration of 40-73 months. In Group II, both CR and CCR were 92.9% and 45.8% respectively. The incidence of patients with Pre-T cell type was higher in this study than in most other reports, and these patients responded favorably to treatment.