Endocrine dysfunction is increasingly recognized as one of the most important aspects of quality of life issues, physical and psychosocial development and overall prognosis in pediatric patients diagnosed with neoplasms as well as in patients s/p bone marrow transplant throughout their lifespan. In addition, several of the new, molecularly designed therapies for neoplasms may interact with endocrine signaling; these include receptors and/or their ligands for growth and/or proliferation factors, and disruptors of steroid hormone interactions. The present study serves as a natural history protocol.