The purpose of this proposal is to support the cooperative group studies at an established children's cancer treatment center at the New York Hospital-Cornell Medical Center. The general goals are to improve patient care through the collaborative chemotherapeutic, surgical and radiotherapy protocols of Children's Cancer Study Group of which the principal investigator has been a member since January 1967. Active protocols include studies in acute lymphoblastic and non-lymphoblastic leukemias, and solid tumors (neuroblastoma, rhabdomyosarcoma, Wilms' tumor, histiocytosis X, Ewing's sarcoma and osteogenic sarcoma). The aim of using new approaches in cancer therapy will hopefully prolong survival in acute lymphoblastic leukemia. The use of new combinations of drugs will hopefully improve remission rates and therefore prolong survival in other less responsive leukemias. Through participation in cooperative survival in other less responsive leukemias. Through participation in cooperative studies the entire medical community engaged in the treatment of children with cancer will have a focal point to provide not only improved patient care but also multidisciplinary teaching and education in the diagnosis and management of malignancies in childhood. This approach will involve medical and nursing students, house officers, staff nurses, hematology-oncology trainees and practicing pediatricians. New approaches will include prospective evaluation of prognostic factors in remission induction and maintenance. The contributions of such factors as the initial WBC at diagnosis, immunocompetence, morphologic and histochemical characteristics and other front end prognostic factors will evaluated in the new ALL study. Immunotherapy with BCG and allogenic leukemia cells will be used in non-ALL. Phase II studies in patients with refractory leukemias and solid tumors will be performed as well.