Subsequent malignant neoplasms in survivors of childhood cancer: Childhood Cancer Survivor Study (CCSS) studies.

Survival of children diagnosed with cancer has improved markedly, because of improvements in chemotherapy and radiation treatment protocols, better diagnosis, and risk classification and improved supportive care. Significant numbers of survivors are now entering their 30s and 40s, and data indicate that excess mortality continues in this group at least as long as 25 to 30 years after treatment. The Childhood Cancer Survivor Study (CCSS) is a large cohort study of 14,054 childhood cancer survivors who have been followed for over 13 years, with a median time from diagnosis now approaching 20 years. This cohort offers an extraordinary opportunity to study therapy-associated subsequent malignant neoplasms, and has allowed improved definition of incidence and risk factors for subsequent breast and thyroid cancer. The collection of genetic samples from members of the cohort has allowed the inclusion of studies of genetic susceptibility to subsequent malignant neoplasms in this population with a uniquely well-defined carcinogenic exposure. The planned formation of a new CCSS cohort, treated with more modern therapy, will allow the extension of these studies to younger populations and will define their experience of subsequent malignant neoplasms.