Health Outcomes in Childhood Cancer Survivors with Congenital Anomalies in the Childhood Cancer Survivor Study

Background: Congenital anomalies are associated with increased risk of childhood cancer. However, there is a knowledge gap regarding health outcomes for childhood cancer survivors with congenital anomalies. Methods: We included childhood cancer survivors from the Childhood Cancer Survivor Study (n=22,247) comparing survivors with and without self-reported anomalies. Using Cox regression, we estimated hazard ratios (HR) and 95% confidence intervals (CI) of chronic health conditions (CHC) classified per the Common Terminology Criteria for Adverse Events (CTCAE) from 1 (mild) to 5 (fatal) and subsequent malignant neoplasms (SMN) comparing survivors by anomaly status. We calculated age-sex-calendar year-specific mortality rates and standardized mortality ratios (SMR) for survivors compared to the US population. Results: Among survivors, 16.9% (n=3,880) reported a congenital anomaly. Survivors with anomalies had a higher rate of any CHC (grades 1-5 HR: 1.24, 95% CI: 1.18-1.31), severe CHCs (grades 3-5 HR: 1.29, 95% CI 1.19-1.40), and multiple CHCs of any grade (≥2 CHCs HR: 1.31, 95% CI 1.24-1.39; ≥3 HR: 1.42, 95% CI 1.33-1.52). Survivors with anomalies had an increased rate of soft-tissue sarcomas (HR: 1.96, 95% CI 1.12-3.44). For deaths related to the original cancer diagnosis, survivors with anomalies (compared to no anomalies) had a lower mortality rate (0.64 vs. 0.90 per 1000 person-years). Conclusions: We identified an increased rate of CHCs and SMNs among childhood cancer survivors with anomalies and lower mortality directly related to the cancer diagnosis. Impact: Future work will focus on evaluation of genetic pathways that increase the risk of CHCs and SMNs.