Attention-deficit/hyperactivity disorder in pediatric cancer survivors: risk and medication use in a nationwide population-based study

Pediatric cancer survivors experience attention or behavioral deficits. This study assessed the risk and medication use of attention-deficit/hyperactivity disorder (ADHD) in pediatric cancer survivors compared with the general population. Using nationwide cohort data from Korea’s National Health Insurance Service, we studied a pediatric cancer population (brain tumors [n = 3,517], acute lymphoblastic leukemia [ALL, n = 2,093], and other tumors [n = 30,639]) diagnosed between 2004 and 2011 and 125,663 healthy children. We analyzed the incidence of ADHD, medication patterns, and factors affecting ADHD using the Cox proportional hazards model and logistic regression analysis. Patients with brain tumors had the highest 10-year ADHD incidence (4.0%, 95% confidence interval [CI] 3.3–4.6) compared with healthy children (2.0%, 95% CI 1.9–2.1), patients with ALL (2.9%, 95% CI 2.2–3.7), and patients with other tumors (2.6%, 95% CI 2.4–2.8). Brain tumor survivors had the highest ADHD risk (hazard ratio [HR] 1.85, 95% CI 1.57–2.17, p < 0.001). Chemotherapy was associated with increased ADHD in children diagnosed at ages 0–3 years (HR 2.89, 95% CI 1.14–7.38, p = 0.03), whereas radiotherapy increased ADHD in patients with ALL (HR 4.10, 95% CI 1.63–10.28, p = 0.003). The use of ADHD medications was significantly higher in younger age groups (0–3 years, HR 2.62, 95% CI 1.98–3.45, p < 0.001; and 4–12 years, HR 3.44, 95% CI 2.30–4.86, p < 0.001) and among brain tumor survivors (HR 1.79, 95% CI 1.32–2.31, p < 0.001). Brain tumor survivors required long-term (> 7 months) ADHD medication (odds ratio 2.06, 95% CI 1.20–3.59, p = 0.01). Pediatric cancer survivors, particularly those with brain tumors or diagnosed at a young age, face a higher risk of ADHD and increased use of ADHD medications. Chemotherapy significantly increases the risk of ADHD in infants and toddlers, whereas radiotherapy increases this risk in patients with ALL. Ongoing monitoring and tailored interventions for high-risk groups are needed.