Cancer Risk by Attained Age among Children with Birth Defects in Arkansas

Background: Few studies have evaluated associations between birth defects and risk of pediatric cancers by age of attainment. Therefore, we assessed the risk of cancer among children with and without birth defects by age at attainment. Methods: We examined cancer risk in children ≤14 years with and without birth defects born between 1996 and 2011 by linking data from the Arkansas Reproductive Health Monitoring System, Arkansas Central Cancer Registry, and birth certificates. Age of attainment for cancer was calculated as person-years from birth to cancer diagnosis, death, or end of study period, whichever occurred first. Using Cox proportional hazards models, we evaluated associations by attained age groups (<1, 1-4, 5-9, and 10-14 years) between: (1) groups of birth defects (any, chromosomal, and non-chromosomal) and any cancer; (2) non-chromosomal birth defects by organ system and any cancer; and (3) non-chromosomal birth defects and subtypes of cancer. Results: In the cohort of 629,086 children, 23,341 (3.7%) children had birth defects and 1,037 (0.2%) children had cancer. For children with non-chromosomal birth defects, specifically cardiovascular and genitourinary, highest risk of any cancer was observed in first year of life (Hazard Ratio [HR] 18.5; 95% confidence interval [CI] 10.1-33.8). For children with chromosomal birth defects, increased cancer risk was observed among those 1-4 years-old (HR 20.0; 95% CI 8.3-48.4). Conclusion: Overall, cancer risk among children with birth defects was highest among those <5 years-old. Our findings, consistent with previous studies, may inform surveillance strategies for children with birth defects.