Study design
We performed a nationwide, retrospective study including all consecutive cases of Danish pediatric patients aged 0-14 years diagnosed with a spinal tumor from January 1st, 1996, to December 31st, 2018. The cohort was identified from a nationwide (population of 5.8 million) registry-based cohort study, previously described in detail, using The Danish Childhood Cancer Registry (DCCR). The DCCR includes all cases classified as neoplasms according to the International Classification of Diseases, 10th edition (ICD-10) (diagnoses DC00-DD48). The DCCR is linked to the Danish National Patient Registry (DNPR), the National Pathology Registry, and the Danish Cancer Registry using the unique national identification number assigned to all permanent residents in Denmark at birth or immigration.