This is a continuation of a cooperative inter-institutional study of cancer in children utilizing multidisciplinary approach to treatment of those types of cancer which are suited to scientific analysis in a reasonable period of time. The studies are designed to provide answers to questions concerning optimum management; and at the same time provide the individual institutions with the added strengths to provide exemplary demonstrative care for its patients and an outreach to provide its community with a referral center for childhood cancer. At the time of writing, there are seven active protocols dealing with leukemia and twelve dealing with solid tumors. The principle protocol for ALL/AUL is designed to determine the relative effectiveness of four regimens to minimize the theoretic "sanctuary" of leukemic cells present at the time of initial induction of complete clinical remission utilizing both chemotherapy and radiation therapy. A specific protocol is available for Wilms' tumor, localized and disseminated neuroblastoma, Histiocytosis, Osteosarcoma for the group alone, as well as for Rhabdomyosarcoma, Ewing's tumor on an intergroup basis. Additional protocols for the study of hepatoma, histiocytosis, and Hodgkin's disease are being formulated. In addition, Phase II studies are on-going utilizing a succession of agents and combinations, such as DTIC, and 5-Azacytadine.