['Intensification chemotherapy improves the prognosis for children with acute lymphoblastic leukemia (ALL), but results in considerable morbidity, primarily due to myelosuppression with resultant neutropenia. Recombinant granulocyte colony-stimulating factor (G-CSF) shortens neutropenia following intensive chemotherapy, but potential benefits in the therapy of ALL remain inadequately explored. Accordingly, a randomized, crossover study was undertaken to clarify this issue.', 'Seventeen children with acute lymphoblastic leukemia or T-cell non-Hodgkin lymphoma and treated on standard protocols were randomized to receive G-CSF following either the first or second intensification blocks of chemotherapy. G-CSF was administered as a single daily subcutaneous injection of 5 mcg/kg from day 9 following the start of intensification therapy, and continued until the neutrophil count exceeded 0.5 x 10(9)/l for 3 days. Study endpoints were days of neutropenia (neutrophils < 1 x 10(9)/l) and severe neutropenia (neutrophils < 0.5 x 10(9)/l), days in hospital, days of fever, and days on antibiotics.', 'There were significant reductions in the duration of neutropenia (95% confidence interval 3.8-8 days, P = 0.0001), severe neutropenia (95% confidence interval 1.8-7.4 days, P = 0.002), and days in hospital (95% confidence interval 0.9-6.3 days, P = 0.01) for children receiving G-CSF. Overall, the duration of neutropenia was longer following the second block (95% confidence interval 2.2-6.4 days, P = 0.0003), but this difference was abolished by G-CSF, and children, receiving G-CSF after the second intensification were more likely to restart maintenance chemotherapy on schedule (P = 0.05).'] Does granulocyte colony-stimulating factor ameliorate toxicity of intensification chemotherapy for acute lymphoblastic leukemia?