ESTRO 2025 - Abstract Book

S674

Clinical - CNS

ESTRO 2025

1491

Digital Poster Clinical Efficacy and Volumetric Evolution of Pituitary Neuroendocrine Tumors Normofractionated External Irradiation Racha-Miloda Hemaidia 1 , Georges Noel 1 , Hélène Cebula 2 , Bernard Goichot 3 1 radiotherapy, ICANS, Strasbourg, France. 2 neurochirurgie, HUS, Strasbourg, France. 3 endocrinology, HUS, Strasbourg, France Purpose/Objective: The objective of this study is to evaluate the local control and hormonal control of normofractionated external irradiation in PiNETs (pituitary neuroendocrine tumors) and to correlate it with the volumetric evolution. The study also aimed to report tolerance and late side effects. Material/Methods: This retrospective monocentric study included patients treated with radiotherapy for pituitary adenomas between 2011 and 2022. Clinical and imaging data were collected, including tumor characteristics, radiotherapy planning, and treatment outcomes. Follow-up assessments were performed periodically to monitor tumor stability, regression, or progression. Tumor volumes were assessed with manual segmentions using Eclipse software, with follow-up MRIs integrated in DICOM format. Results: Among the 35 patients who received radiotherapy, 48.6% had a functional PiNETs. The median follow-up was 54.9 months. Results showed that at 24 and 60 months, local relapse-free survival was 97.1% (95% CI: 80.9–99.6%). Hormonal normalization rates at 24 and 50 months were 34.1% (95% CI: 15.5–65.9%) and 62.9% (95% CI: 36.1– 88.9%). Volumetric evolution analysis revealed a median reduction of -31.5% (-90% to +12.0%) or -1.25 cc (-22.8 to +2 cc) at the last follow-up, and a reduction of -17% (-79% to +20%) or -0.75 cc (-19.9 to +0.1 cc) at two years.The comparative analyses showed no difference between patients who experienced a high reduction in size over than 50%. The functional PiNETs that normalized their hypersecretion did not exhibit a more significant volumetric reduction compared to those that did not normalize their function. The acute tolerance of the treatment was excellent, although some late side effects were reported, including a 14.3% rate of new pituitary deficiency requiring supplementation, with central deficit-free survival at 24 months being 91.3% (95% CI: 75.5–97.1%). Cognitively, 4 out of 9 patients (25.7%) reporting memory impairment underwent neuropsychological evaluation. One was normal, and another found a cause unrelated to radiotherapy. For auditory deficits, of 11 complaints (31.34%), 4 underwent ENT evaluation. One showed radiation-induced tubal catarrh, two were attributed to presbycusis, and one was normal. All patients adhered to the dose constraint of Dmean <30 Gy; however, a stricter constraint of Dmean <10 Gy was not met in 54.5% (6/11) of patients. dosimetric analysis were performed to critically assess the causality of side effects attributed to radiotherapy. Conclusion: Normofractionated radiotherapy for PiNETs demonstrated satisfactory outcomes in terms of tumor volume reduction, clinical and hormonal control.The incidence of late adverse effects remains within acceptable bounds.

Keywords: PiNets,pituitary,adenoma