Second Malignant Neoplasms in Five-Year Survivors of Childhood Cancer: Childhood Cancer Survivor Study

Background: Because survival rates among childhood cancer patients are increasing, assessing the risk of second and sub-sequent malignant neoplasms (SMNs) is ever more impor-tant. Using the Childhood Cancer Survivor Study cohort, we identified the risk of SMNs. Methods: A retrospective cohort of 13 581 children diagnosed with common cancers before age 21 years and surviving at least 5 years was constructed with the use of data from patients treated at 25 U.S. and Canadian institutions. SMNs were ascertained through self-administered questionnaires and verified by pathology re-ports. Information on therapeutic exposures was abstracted from medical records. The risk of SMN was evaluated by standardized incidence ratios (SIRs) and excess absolute risk. Poisson multiple regression models were used to assess the impact of host and therapy factors on the risk of devel