Increased Incidence and Improved Survival of Ewing and Ewing‐Like Sarcomas in Children and Young Adolescents in the Netherlands Since the 1990s: A Population‐Based Study

Against the background of therapeutic improvements and centralization of care, we evaluated epidemiological trends in Ewing and Ewing-like sarcomas (ES) among children and young adolescents in the Netherlands over three decades. Data on 464 pediatric patients (0-17 years) diagnosed with ES in the Netherlands between 1990 and 2018 were obtained from the Netherlands Cancer Registry, with follow-up until February 2024. Incidence trends were evaluated by calculating the average annual percentage change (AAPC). A Cox regression model was used to assess the effect of sex, age, stage at diagnosis, and tissue-specific tumor site on changes in 5-year observed overall survival (OS) over time. Between 1990 and 2018, on average 16 pediatric patients were diagnosed with ES yearly. The age-standardized incidence rate increased by 2.1% annually, rising from 3.7 per million person-years in 1990-1999 to 5.2 in 2010-2018. Over time, the use of local therapy combined with chemotherapy increased from 75% in 1990-1999 to 94% in 2010-2018. Five-year OS improved from 56% (1990-1999) to 70% (2010-2018), and the 10-year OS increased from 51% to 65% in these periods. Multivariable analyzes confirmed a lower risk of mortality from ES in 2010-2018 (HR 0.4, 95% CI 0.3-0.6) compared to 1990-1999. ES incidence increased alongside improved survival, likely influenced by various factors, including advancements in diagnostics, treatment, supportive care, and follow-up. Nevertheless, patients with metastatic disease and older children continue to experience higher mortality risks, highlighting the importance of ongoing research and targeted treatments to further improve pediatric ES outcomes.