Long-term population-based risks of breast cancer after childhood cancer.

Previous studies have reported substantially increased risks of breast cancer among survivors of childhood cancer at 10-20 years posttreatment. Whether these excess risks are sustained beyond 40 years of age when general population incidence of breast cancer begins its steep increase is largely unknown. We quantified the risk of breast cancer in adult female survivors with considerably more survivors followed-up beyond 40 years of age than previously available.