Granulocyte colony stimulating factor permits dose intensification by interval compression in the treatment of Ewing's sarcomas and soft tissue sarcomas in children.

71 children with sarcomas were treated in a prospective pilot study to determine whether granulocyte colony stimulating factor (G-CSF) permits compression of the interval between chemotherapy cycles. Patients had Ewing's sarcoma/primitive neuroectodermal tumour (PNET), rhabdomyosarcoma, non-rhabdo soft tissue sarcomas or other advanced soft tissue tumours. The chemotherapy alternated vincristine-doxorubicin-cyclophosphamide and ifosfamide-etoposide, with G-CSF between courses. Therapy had two phases: induction (six cycles) and continuation (six cycles), which included primary tumour treatment with surgery and/or radiation. Chemotherapy cycles began every 14 days, or upon absolute neutrophil count (ANC) and platelet count recovery. The median chemotherapy cycle interval was 16 (11-48) days in the induction phase, with a median average relative dose intensification (ARDI) of 1.27 compared with every-21-day therapy. In the continuation phase, the median cycle interval was 21 days, with a median ARDI of 1.10. Radiation therapy prolonged chemotherapy intervals, whilst erythropoietin shortened them. Toxicity was modest for such chemotherapy. Event-free survival is comparable with or superior to that in recent large studies. G-CSF permits intensification of this regimen through interval compression. The impact of this approach on efficacy remains to be determined in a randomised trial.