The Childhood Cancer Survivor Study (CCSS) is a collaborative, multi-institutional study funded by the National Cancer Institute since 1993. The goal of CCSS is to investigate the long-term morbidity and mortality associated with the treatment regimens for children and adolescents treated for cancer during the past 30 years. It was created to gain new knowledge about the long-term effects of cancer and therapy and to educate survivors and the medical community about the potential impacts of cancer diagnosis and treatment. The results obtained from CCSS are used to help design treatment protocols and interventions that will result in an increase in survival while minimizing the harmful late effects. This research is also used to develop and expand programs for early detection and prevention of late effects in children and adolescent cancer survivors. The CCSS consists of over 14,000 participants diagnosed with cancer between 1970 to 1986 who have survived at least 5 years after treatment for cancer. CCSS is expanding their study cohort to include children and adolescents who had been diagnosed between 1987 to 1999 in order to include survivors of more modern cancer treatment. CCSS consists of 27 clinical centers in the United States and Canada.