Cancer Incidence and Risk in Children and Adolescents With Intellectual Disability in South Korea.

[OBJECTIVE] To evaluate cancer risk and identify distinctive cancer patterns in children and adolescents with intellectual disability (ID) in South Korea, where comprehensive research in this population remains limited.

[DESIGN] Retrospective cohort study.

[SETTING] Nationwide population-based data from the National Health Insurance Service-National Health Information Database (NHIS-NHID) in South Korea (2004-2021).

[PARTICIPANTS] This study included individuals (N=75,491) with ID aged 2-18 years and 917,699 age- and sex-matched controls without ID (1:10 matching ratio to maximize statistical power).

[INTERVENTIONS] Not applicable.

[MAIN OUTCOME MEASURES] Cancer incidence and associated risk factors, including comorbidities, demographic characteristics, and socioeconomic status, analyzed using Cox proportional hazard models.

[RESULTS] Children and adolescents with ID had a significantly higher overall cancer incidence and risk compared to the control group (adjusted hazard ratio [HR]: 1.1; 95% confidence interval [CI]: 1.005-1.204). Those with medical comorbidities faced an even greater risk (adjusted HR: 1.96; 95% CI, 1.75-2.194). Significant risk factors included older age (16-≤18y vs 2-<6y: HR 3.529; 95% CI, 3.321-3.749) and lower socioeconomic status (medical aid vs high-income: HR 0.863; 95% CI, 0.788-0.945). The top 5 cancer sites in the ID group were renal pelvis and ureter; heart, mediastinum, and pleura; acute lymphoblastic leukemia; brain; and ovary.

[CONCLUSIONS] Children and adolescents with ID in South Korea exhibit a distinct cancer risk profile, with elevated cancer incidence compared to the control group. Tailored cancer prevention, early detection strategies, and health care utilization policies are essential to address these needs of this vulnerable group.