The purpose of this proposal is to conduct cooperative group studies of an established multidisciplinary cancer treatment program for children at The New York Hospital-Cornell Medical Center. The general goals are to improve patient care and survival of children with cancer through the collaborative chemotherapeutic, surgical and radiotherapy protocols of Children's Cancer Study Group (CCSG). Active protocols include studies in acute lymphoblastic and non-lymphoblastic leukemias and solid tumors (brain tumors, Wilms' tumor, neuroblastoma, rhabdomyosarcoma, histiocytosis X, Ewing's sarcoma, osteosarcoma and hepatoma). The aim of using new approaches in cancer therapy is 1) to prolong long term survival in acute lymphoblastic leukemia; 2) to improve remission rates in less responsive leukemias and solid tumors and 3) to minimize adverse effects of therapy in patients with favorable prognosis and improve the response rate in patients with a poor prognosis by more aggressive therapy or new modalities of therapy. Through participation in cooperative studies the entire medical community engaged in cancer therapy will have a focal point to provide multidisciplinary teaching and education in the diagnosis and management of cancer in children. New approaches will include prospective evaluation of prognostic factors in remission induction and maintenance in ALL; Immunotherapy with BCG and allogenic leukemia cells will be used in non-ALL, and BCG will be used with chemotherapy in patients with metastatic neuroblastoma. Phase II agents will be used in patients with refractory leukemias and solid tumors.