Spanish Paediatric Haematology and Oncology Survival Results and Trends, 1999-2022

Background: Childhood cancer is the leading cause of natural death among children in high-income countries, despite treatment improvements. The Spanish Registry of Childhood Tumours (RETI-SEHOP) systematically records all cases treated within the network of SEHOP units. Using RETI-SEHOP data, we evaluated survival trends to assess progress in patient care, both overall and by tumour. Methods: A total of 20,534 childhood cancer cases (0-14 years) were recorded across the period 1999-2021. The 1-, 3-, and 5-year overall survival (OS) were estimated using the Kaplan-Meier method, applying the cohort approach for 1999-2018 and the period approach for 2019-2022. OS by age and sex was analysed in the recent 2009-2018 incidence cohort. Age-adjusted OS time trends were examined using joinpoint Cox models for 1999-2022. Results: For all tumours combined, 5-year OS increased from 75.4% to 84.6% between 1999-2003 and 2019-2022. While positive trends were identified for all haematological malignancies examined, a more varied scenario was evident for solid tumours, as ependymomas improved fastest (1.51 points annually), and sarcomas, except for rhabdomyosarcoma, remained stagnant. Conclusions: Our results reflect a period characterised by a combination of new therapeutic developments, improved diagnostics, and more refined risk stratification, which has ultimately led to a reduction in disease-related mortality.