This study allowed for a long-term follow up of both childhood and young adult cancer patients aged below 34 years at cancer diagnosis by registry linkage, offering new insights especially on young adult cancer patients.

Both childhood and young adult patients showed an increased likelihood of purchasing medication associated with metabolic syndrome compared to siblings with highest hazard ratios found after childhood cancer.

Purchases of medications associated with metabolic syndrome were highly dependent on the cancer diagnosis and age at cancer diagnosis.

These findings can contribute to an improved cardiovascular and metabolic follow-up after childhood and young adult cancer to possibly reduce cardiovascular morbidity and excess mortality in this growing population at risk.