Childhood, adolescent and young adult cancer and the prevalence of diagnosed autism or attention deficit hyperactivity disorder: A systematic review and meta-analysis

Objectives: Attentional and social differences are common in children, teenagers and young adults (CTYA) impacted by cancer.This systematic review and meta-analysis examined the prevalence of autism and ADHD in CTYA affected by cancer or benign brain tumours. Methods:The review was reported according to PRISMA guidelines.Studies were exported from databases up to April 2025.Those reporting on CTYA from birth to 39 years at the time of cancer diagnosis, and a diagnosis of autism or ADHD, were eligible for inclusion.Following narrative review, random-effects meta-analyses calculated the overall prevalence of autism and ADHD.The JBI Critical Appraisal Checklist for Studies Reporting Prevalence Data identified higher quality studies for sensitivity analyses. Results:Of the 34 studies eligible for inclusion in the review, 25 contributed to the metaanalyses.ADHD prevalence in 6733 CTYA with cancer was 8.91% (6.32-12.43%),increasing to 8.99% (5.70-13.91%)on sensitivity analysis.ADHD prevalence in those with CNS tumours was 9.61% (6.44-14.12%).Autism prevalence (3103 CTYA) was 1.52% (0.72-3.20%), reducing to 1.32% (0.56-3.09%) on sensitivity analysis.Autism prevalence in those with CNS tumours was 3.56% (2.16-5.83%).Cancer type contributed to high between-study heterogeneity.The Grading of Recommendations, Assessment, Development and Evaluation (GRADE) strength of evidence was 'low', increasing to 'moderate' for the sensitivity analyses.Conclusions: Summary estimates indicate a higher prevalence of ADHD in CTYA with cancer, and of autism in those with CNS tumours, compared to the general population.Timely recognition of autism and ADHD in this population promotes optimisation of social, educational and health outcomes.