This study will determine the prevalence of endocrine-related side effects in children who have been treated for cancer and establish a database and registry organized according to cancer diagnosis, treatments and endocrine side effects. In children, the endocrine system, which includes glands and hormones that help to control metabolism, growth, development and reproduction, is particularly vulnerable to long-term side effects associated with cancer and its treatments. The study will also serve to help train medical fellows, residents and students in identifying and managing endocrine abnormalities in children who have been diagnosed with and treated for cancer.