Abstract
BACKGROUND: The goal of this study was to describe the incidence, characteristics, and outcomes of secondary malignant neoplasms (SMN) in survivors of Wilms tumor. PROCEDURES: Patients who were 0-20 years of age at time of primary diagnosis with Wilms tumor and reported to the Surveillance, Epidemiology, and End Results [SEER] program between 1973 and 2011 were eligible for inclusion in the cohort. We used competing risks methods to estimate the cumulative incidence of SMNs and assess contributing factors for developing SMN. We estimated standardized incidence ratios (SIR), absolute excess risk and overall survival after SMN using standard methods. RESULTS: Within the SEER database, 2,851 patients were diagnosed with Wilms tumor as their first malignancy. Of these, 34 patients were reported to have a SMN. Cumulative incidence of for a secondary malignancy was 0.6% (95% confidence interval [95% CI] 0.3-1.0%) at 10 years, 1.6% (95% CI 1.0-2.3%) at 20 years, and 3.8% (95% CI 2.4-5.9%) at 30 years. Median time from primary diagnosis to SMN diagnosis was 12.5 years. SIR for SMN for survivors of Wilms tumor was 3.4 (95% CI 2.2-4.9) with an absolute excess risk of 7.6 per 10,000 persons per year. Exposure to radiation did not significantly increase risk for development of second malignancy. Overall survival for patients with SMN was 64.5% at 5 years. CONCLUSION: Survivors of Wilms tumor are at an increased risk of SMN compared to the general population, but the added risk is relatively small compared to other pediatric cancers.