Search

Background:Pediatric safety margins are generally based on data from adult studies; however, adult-based margins might be too large for children. The aim of this study was to quantify and compare interfractional organ position variation in children and adults. Material and methods:For 35 children and 35 adults treated with thoracic/abdominal irradiation, 850 (range 5–30 per patient) retrospectively collected cone beam CT images were registered to the reference CT that was used for radiation treatment planning purposes. Renal position variation was assessed in three orthogonal directions and summarized as 3D vector lengths. Diaphragmatic position variation was assessed in the cranio-caudal (CC) direction only. We calculated means and SDs to estimate group systematic (Σ) and random errors (σ) of organ position variation. Finally, we investigated possible correlations between organ position variation and patients’ height. Results:Interfractional organ position variation was different in children and adults. Median 3D right and left kidney vector lengths were significantly smaller in children than in adults (2.8, 2.9 mm vs. 5.6, 5.2 mm, respectively;p < .05). Generally, the pediatric Σ and σ were significantly smaller than in adults (p < .007). Overall and within both subgroups, organ position variation and patients’ height were only negligibly correlated. Conclusions:Interfractional renal and diaphragmatic position variation in children is smaller than in adults indicating that pediatric margins should be defined differently from adult margins. Underlying mechanisms and other components of geometrical uncertainties need further investigation to explain differences and to appropriately define pediatric safety margins. [ABSTRACT FROM AUTHOR]

Adolescents and young adults (AYAs) with Ewing sarcoma have a worse prognosis than children. Population-based survival evaluations stratifying findings by important clinical factors are, however, limited. This Dutch population study comprehensively compared survival of children and AYAs with Ewing sarcoma over three decades considering diagnostic period, tissue of origin, tumor site, and disease stage. Data on all children (0–17 years, N = 463) and AYAs (18–39 years, N = 379) diagnosed with Ewing sarcoma in the Netherlands between 1990–2018 were collected from the Netherlands Cancer Registry with follow-up until February 2023. Five-year relative survival was calculated using the cohort method. Multivariable analyses were conducted through Poisson regression. Children with Ewing sarcoma had a significantly higher 5-year relative survival than AYAs (65 % vs. 44 %). An increasing trend in survival was noted reaching 70 % in children and 53 % in AYAs in 2010–2018. Results were similar for Ewing bone sarcoma and extraosseous Ewing sarcoma. AYAs had a poorer prognosis than children for most tumor sites and regardless of disease stage. Survival probabilities were 60 % vs. 78 % for localized disease and 20 % vs. 33 % for metastatic disease. Multivariable-regression analysis, adjusted for follow-up time, diagnostic period, sex, disease stage, and tumor site, confirmed increased excess mortality among AYAs compared with children (excess HR: 1.7, 95 % CI: 1.3–2.1). Despite survival improvements since the 1990s, AYAs with Ewing sarcoma in the Netherlands continue to fare considerably worse than children. This survival disparity was present irrespective of tissue of origin, tumor site, and disease stage • Children with Ewing sarcoma in the Netherlands had better overall survival than AYAs. • Five-year survival increased over time to 70 % in children and 53 % in AYAs in 2010-2018. • The survival difference between children and AYAs did not change over time. • Survival was similar for Ewing bone sarcoma and primary extraosseous Ewing sarcoma. • AYAs had a worse prognosis than children irrespective of tumor site and disease stage. [ABSTRACT FROM AUTHOR]