Of 2947 children with acute lymphocytic leukemia (ALL), treated during three consecutive studies of the Pediatric Oncology Group (1974-1986), 52 (1.8%) had Down's Syndrome (DS). Comparison of clinical and laboratory characteristics showed no significant differences in leukocyte count, racial distribution, sex ratio, platelet count, incidence of mediastinal mass, lymphadenopathy or hepatosplenomegaly, or percentage of blood or bone marrow blasts for children with ALL with or without Down's Syndrome (DS-ALL or NDS-ALL, respectively). However, children with DS-ALL were slightly older at the time of presentation and had higher hemoglobin values. The relative frequency of each major immunophenotype (early pre-B, pre-B, T, or B) was also comparable for patients with or without DS. For this report, treatment regimens were categorized as either conventional (no consolidation therapy) or intensive. Cox regression analysis revealed that the presence of DS, a higher leukocyte count, black race, or age older than 10 years was independently associated with a poorer event-free survival (EFS) for children treated with conventional chemotherapy. However, for the cohort of children who received intensive chemotherapy, DS was no longer an independent risk factor. In fact, event-free survival (EFS) was markedly improved to a level comparable with that observed in the children diagnosed as having NDS-ALL. On the other hand, serious toxicity, requiring interruption of treatment, was significantly more frequent in the intensively treated children with DS compared with similarly treated patients with NDS-ALL, although deaths resulting from toxicity occurred infrequently. Cancer 67:1057-1063,1991.
HILDREN WITH Down's Syndrome (DS) have a C markedly increased risk of acute leukemias ( 10-30 times that of the general population).','
The relative frequency of lymphoid and myeloid leu-kemias among children with DS varies in different studi e ~. ~-~ Although recent data indicates that children with DS have an increased risk of both types of leukemia, the distribution of French-American-British (FAB) morpho-