Increased post‐induction intensification improves outcome in children and adolescents with a markedly elevated white blood cell count (≥200 × 10 9 /l) with T cell acute lymphoblastic leukaemia but not B cell disease: a report from the C hildren's O ncology G roup

Summary Children and adolescents presenting with a markedly elevated white blood cell ( ME WBC ) count ( WBC ≥200 × 10 9 /l) comprise a unique subset of high‐risk patients with acute lymphoblastic leukaemia ( ALL ). We evaluated the outcomes of the 251 patients (12% of the study population) with ME WBC treated on the Children's Cancer Group‐1961 protocol. Patients were evaluated for early response to treatment by bone marrow morphology; those with a rapid early response were randomized to treatment regimens testing longer and stronger post‐induction therapy. We found that ME WBC patients have a poorer outcome compared to those patients presenting with a WBC <200 × 10 9 /l (5‐year event‐free survival 62% vs. 73%, P  = 0·0005). Longer duration of therapy worsened outcome for T cell ME WBC with a trend to poorer outcome in B ‐ ALL ME WBC patients. Augmented therapy benefits T cell ME WBC patients, similar to the entire study cohort, however, there appeared to be no impact on survival for B ‐ ALL ME WBC patients. ME WBC was not a prognostic factor for T cell patients. In patients with high risk features, B lineage disease in association with ME WBC has a negative impact on survival.