ESTRO 2025 - Abstract Book

S740

Clinical - CNS

ESTRO 2025

4071

Digital Poster Hypofractionated radiosurgery for functioning and non-functioning pituitary adenomas after surgery: Our working experience with Cyberknife unit. Julen Azcona Martin 1 , Marta Camacho Manzanares 1 , Eva Fernández Lizarbe 1 , Ignacio Maria Gómez Paloma 1 , Mercedes Martín Sánchez 1 , David Sevillano Martínez 2 , Juan David García Fuentes 2 , Adrian Durango 1 , María Dolores Espinosa 1 , Isabel Alvira 1 , Margarita Martín 2 , Patricia Martín Nieto 1 , Marina Alarza Cano 1 , Rubén Chillida Rey 2 , Sonsoles Sancho García 1 1 Radiation Oncology, Ramón y Cajal University Hospital, Madrid, Spain. 2 Radiophysicis, Ramón y Cajal University Hospital, Madrid, Spain Purpose/Objective: The aim of this report is to evaluate and present the clinical outcomes and tolerance profile of hypofractionated radiosurgery for both functioning and non-functioning pituitary adenomas after partial resection. The original single fraction radiosurgery has been limited to those cases presenting small and far from the organs at risk lesions. Using the new intrafraction image guided and frameless technologies, as the Robotic Radiosurgery Unit Cyberknife, we are now allowed to deliver radiosurgery in 3-5 fractions for more complex cases. Material/Methods: Between June 2020 and June 2024 a total of 30 patients (13 women and 17 men) with a median age of 48,5 years were treated post-surgically with radiotherapy in our center. 27 patients presented macroadenomas and only 3 microadenomas; 13 were intrasellar (43,3%), 14 presented cavernous sinus invasion (46,7%) and 3 extrasellar (10%). 7 of them were functioning adenomas (2 ACTH-secreting, 2 prolactinoma and 3 GH-secreting). Radiotherapy indications after surgery were either remanent tumor growing, biochemical failure or poor systemic treatment tolerance A non-contrasted CT scan and a magnetic resonance (MRI) with T1, T2 and T1 with contrast and fat suppressing sequences were used in every patient for treatment planning. Results: The most commonly used fractionations were 24 Gy in 3 fractions and 25 Gy in 5 fractions, both used in 9 cases. For the 24 Gy in 3 fr we reached median max doses of 33,61 Gy in hypophysis, 13,8 Gy in optic chiasm; 8 Gy left optic nerve and 10 Gy in right optic nerve. Whereas for the 25 Gy in 5 fractions median max doses were 34,15Gy in hypophysis, 22,79 Gy in optic chiasm; 9,73 Gy left optic nerve and 24 Gy in right optic nerve. The median follow up was 26 months (7-47 months). We have observed that 40% of the adenomas have decreased in size, and the rest have remained stable without any growing. Two out of six functioning patients have achieved biochemical control. The tolerance of the treatment was excellent. Only in 10 patients (43,5%) acute toxicity was reported consisting of grade 1-2 transient cephalea. Not chronic toxicity was reported except for a single case of transient diplopia with no visual acuity lost, completely recovered after steroids. Conclusion: Hypofractionated radiosurgery for pituitary adenomas appears to be a feasible and safe option for patients with large volumes or sinus involvement. In our series we report radiological response or stability for all the treated patients with acceptable acute toxicity.

Keywords: Radiosurgery, Pituitary