Assessing Late Outcomes of Advances in Radiotherapy for Paediatric Cancers: Study Protocol of the “HARMONIC-RT” European Registry (NCT 04746729)

Each year, approximately 35,000 children and adolescents are diagnosed with cancer in Europe [1]. Overall, the five-year survival rate now exceeds 80% [2]. However, the burden of cancer and treatment-related sequelae is significant. Paediatric cancer survivors have a 5-times higher risk of developing severe, disabling or fatal health conditions by the age of 50 years compared to their siblings [3]. External beam radiation therapy technique (EBRT) is an important risk factor for sequelae such as second and subsequent primary cancer (SPC), cardio- and neurovascular diseases and endocrinopathies, which typically occur after some latency [4–8].