Risk of second malignant neoplasms (SMN) 20 years after childhood cancer: The updated experience of the Childhood Cancer Survivor Study (CCSS)

8509 Background: Survivors of childhood and adolescent malignancies are at increased risk for SMN but there are limited data regarding risks 20+ years following diagnosis. Objectives: To determine the incidence and risk factors for SMNs in a well-defined cohort of childhood cancer survivors. Methods: Among the CCSS cohort of 20,720 5-yr survivors (diagnosed 1970–86), SMNs are ascertained and verified by pathology reports. Age- and sex-standardized incidence ratios (SIR) were calculated using US Surveillance, Epidemiology and End Results (SEER) data. Results: As of June 2003, there were 914 verified SMNs among 14,352 survivors with 198,277 person years of follow-up (including 404 cases of non-melanoma skin cancer (NMSC, 4.3% 20-yr cumulative incidence). Excluding NMSC from the analyses, the overall SIR is 3.9 (95% CI 3.5, 4.2) with a 20-yr cumulative incidence of 5.2%. The 20-yr cumulative incidence of SMN, by original diagnosis: Hodgkin disease (13.9%), Bone tumor (6.6%), Soft tissue sarcoma (5.8%), CNS t...