Each year in the United States, nearly 70 000 individuals between the ages of 15 and 40 years are diagnosed with cancer. Although overall cancer survival rates among pediatric and older adult patients have increased in recent decades, there has been little improvement in survival of adolescent and young adult (AYA) cancer patients since 1975 when collected data became adequate to evaluate this issue. In 2006, the AYA Oncology Progress Review Group made recommendations for addressing the needs of this population that were later implemented by the LIVESTRONG Young Adult Alliance. One of their overriding questions was whether the cancers seen in AYA patients were biologically different than the same cancers in adult and/or pediatric patients. On June 9-10, 2009, the National Cancer Institute (NCI) and the Lance Armstrong Foundation (LAF) convened a workshop in Bethesda, MD, entitled "Unique Characteristics of AYA Cancers: Focus on Acute Lymphocytic Leukemia (ALL), Breast Cancer and Colon Cancer" that aimed to examine the current state of basic and translational research on these cancers and to discuss the next steps to improve their prognosis and treatment.