Poor-prognosis acute lymphoblastic leukemias.

Burkitt's-type leukemias have specific cytologic, immunologic, and cytogenetic characteristics. Initial symptomatology frequently includes abdominal tumors and initial CNS involvement. Despite intensive treatment including high-dose cyclophosphamide, prognosis remains poor in most patients because of failures to achieve complete remission (CR) or because of early relapses, especially CNS relapses. Class III acute lymphoblastic leukemia in children is defined by the presence of two or more unfavorable parameters and recent progress has been achieved by intensive therapy. Cox's multifactorial analysis allows improved discrimination. A phase I protocol for increased-risk leukemias, including testis preventive irradiation and monthly reinductions without continuous maintenance for the first 6 months of CR, seems promising.