The purpose of this project is to identify optimal treatment for malignant diseases in children by means of collaborative studies within the Southwest Oncology Group. These studies utilize standardized protocols variously designed to determine (a) dosage and toxicity of new drugs (Phase I), (b) efficacy of selected drugs for a given disease by means of randomized clinical trials (Phase III). Statistically valid selection of those treatments which are most effective in prolonging survival of children with malignant diseases cannot be achieved in a reasonable period of time within most single institutions. Interinstitutional collaborative studies provide a more efficient means of achieving such a goal. In addition, collaborative studies promote interdisciplinary functions, teaching, and clinical research within the participating institution and introduce optimal approaches to diagnosis and treatment of cancer to referring physicians and others at the community level. The Pediatric Department of the University of North Carolina School of Medicine, represented by the Division of Hematology-Oncology, has been a probationary member of the Southwest Oncology Group since 1972 and is now eligible for full membership through 88 registrations from 10/26/72 to 4/19/74 (largely Phase III studies). The level of support requested for this project is based on an expected continuing registration rate of 50 per year.