S381
Clinical - CNS
ESTRO 2026
Digital Poster Highlight 3468
A Risk Stratification Approach to Screening for Hypopituitarism Based on Pituitary Radiation Dose in Adult Survivors of non-pituitary Brain Tumours Darran McDonald 1,2 , Liam O'Connell 3 , Maria Tomkins 1,2 , Tara McDonnell 1,2 , Niamh McDermott 1 , Jack Lee 1 , Clare Carthy 1 , Mary Moore 1 , Amar Agha 1,2 , Donncha O'Brien 4 , Kieron Sweeney 4 , Stephen MacNally 4 , Mohen Javadpour 4 , Clare Faul 3 , David Fitzpatrick 3 , Michael O'Reilly 1,2 , David Fitzpatrick 3 , Mark Sherlock 1,2 1 Endocrinology, Beaumont Hospital, Dublin, Ireland. 2 Endocrinology, Royal College of Surgeons, Ireland, Dublin, Ireland. 3 Radiation Oncology, St Lukes Radiation Oncology Network, Dublin, Ireland. 4 Neurosurgery, Beaumont Hospital, Dublin, Ireland Purpose/Objective: Radiation induced hypopituitarism (RIH) represents a significant late complication of cranial radiotherapy with the potential to substantially impair quality of life and contribute to long term morbidity among brain tumour survivors. Despite recognition of this risk, evidence guiding the stratification of patients according to their likelihood of developing RIH remains limited, particularly among adults treated with non-pituitary brain tumours. Our objective was to develop a pituitary dose based risk stratification model and evaluate its ability to predict RIH in adult brain tumour survivors treated with radiotherapy. Material/Methods: Pituitary hormone function was evaluated in a total of 140 patients who received brain radiotherapy between 2011 and 2022, including a retrospective cohort (n = 86) and a prospective cohort (n = 54). Radiotherapy was delivered using either volumetric arc radiotherapy (VMAT) or intensity modulated radiotherapy (IMRT). The dose prescription was between 50 Gy to 60 Gy in fractions of between 1.8 Gy to 2 Gy. Participants were grouped according to their mean pituitary radiation dose: low-dose ( < 30 Gy), intermediate-dose (30–44.9 Gy), and high-dose ( > 45 Gy). The median age at radiotherapy was 39.7 years (IQR 30.5-49.8) and follow-up interval following radiotherapy was 60.5 months (IQR 36.0-83.0). Groups comprised of low dose (n= 33), middle dose (n=30) and high dose (n=74) survivors.
Conclusion: Location and time-to-recurrence were not impacted by the amount of FHR included in the CTV, with failures predominantly central. The inclusion of FHR modestly expanded target volumes but did not provide a measurable advantage in recurrence coverage, dose distribution, or survival outcomes. Within the setting of small-margin adaptive MR-guided RT, these findings suggest that omitting the FHR does not increase the risk of early or marginal failures. References: 1. Detsky J, Chan AW, Palhares DM, et al. MR-Linac On- Line Weekly Adaptive Radiotherapy for High Grade Glioma (HGG): Results from the UNITED Single Arm Phase II Trial. International Journal of Radiation Oncology, Biology, Physics. 2024;120(2):S4. doi:10.1016/j.ijrobp.2024.08.016 Keywords: Glioblastoma, Adaptive Radiotherapy, MR- LINAC
Made with FlippingBook - Share PDF online