Utility of genomic testing in children, adolescents, and young adults with cancer.

Genomic testing can inform the diagnosis and personalise management of cancers in children, adolescents, and young adults (CAYA). This scoping review explored the clinical utility and impact of genomic testing in general CAYA cancer cohorts. Relevant records published in English between 2017-2024 were identified by searching PubMed. 36 studies (32 original articles; 4 reviews) were identified on genomic testing in CAYA cancers, most of which were advanced cancers. Studies internationally reported that approximately 16-18% of CAYAs with cancer carry an associated pathogenic germline variant where 40% are de-novo, and can guide treatment (eg, DNA repair gene variants). Somatic variants, predominantly copy number or structural rearrangements, inform diagnosis in up to 95% of primary cancers. Between 18-69% of patients have a somatic variant with a matched therapy, but only one third receive the genomic-guided recommendation, predominantly due to declining patient condition. Few studies evaluated the impact of matched therapies on response and survival. Combining comprehensive DNA and RNA sequencing maximises sensitivity. Circulating tumour DNA was detected in most primary cancers and shows high concordance with tumour tissue. In conclusion, genomic testing of CAYA cancers is feasible, informs diagnoses and guides personalised care. Further research is needed on response to genomic-guided treatments.