ESTRO 2025 - Abstract Book

S679

Clinical - CNS

ESTRO 2025

1 Radiation Oncology, Apollo Proton Cancer Centre, Chennai, India. 2 Radiation Oncology, Tata Memorial Centre, Mumbai, India. 3 Psychiatry, Tata Memorial Centre, Mumbai, India. 4 Endocrinology, Seth G S Medical College,. K.E.M.Hospital, Mumbai, India Purpose/Objective: The evolving treatment paradigm in children and adolescents with craniopharyngioma (CP) aims at minimizing late functional sequelae while not compromising durable tumour control. There is a paucity of prospective data regarding long-term 10-year tumour control rates and survival in these patients. Material/Methods: A randomized controlled trial was conducted in 200 children and young adolescents with benign brain tumors to evaluate the efficacy of stereotactic conformal radiotherapy (SCRT) compared to conventional radiotherapy (ConvRT). This study reports a long-term analysis of a subset of 82 patients diagnosed with CP (SCRT: 39, ConvRT: 43), aiming to assess the clinical impact of dosimetric sparing with high-precision SCRT on neurocognitive function, endocrine function, and survival. All patients received 54 Gy in 30 fractions over 6 weeks, delivered via either SCRT or ConvRT. Patients were longitudinally assessed from baseline (pre-radiotherapy) through five years post-treatment to compare the incidence and severity of neurocognitive and neuroendocrine dysfunction between the two groups (primary endpoints). Overall survival (OS) and local control (LC) were monitored through continuous follow-up. Results: In the present study cohort of 82 patients with CP, the median age was 13 years (IQR= 9-17 years). The 10-year OS and LC rates were 86.4% (95% CI: 78.4%–95.3%) and 92.7% (95% CI: 85.9%–100%), respectively, with no significant difference between the treatment arms. Patients treated with SCRT showed significant improvement in mean full scale IQ (difference in slope=3.3 points per year, 95% CI: 5.8 – 0.8; p= 0.01) and Performance quotient (difference in slope=3.6, 95% CI: 6.26 – 0.15; p= 0.04) compared to those treated with ConvRT. The estimated rate of freedom from cognitive decline (defined as a 5-point drop in any IQ domain) at 5 years was higher with SCRT (66.6% vs. 38.2%; HR = 0.41, 95% CI: 0.18–0.92, p = 0.03). Age (<15 years vs. ≥15 years) was a significant predictor of neurocognitive outcomes in multivariable analyses (p = 0.002), and the cognitive benefits of SCRT were consistent across age groups. Patients treated with SCRT also experienced a significantly lower cumulative incidence of new neuroendocrine dysfunctions (25.7% in SCRT vs. 48.8% in ConvRT; p = 0.029). Conclusion: This prospective clinical investigation provides robust evidence supporting the use of precision radiotherapy for achieving excellent durable long term tumour control and survival in CP’s. SCRT provides superior long-term preservation of neurocognitive and endocrine functions compared to conventional RT, without compromising long term survival or tumour control.

Keywords: CNS, paediatric, conformal, craniopharyngioma

1571

Digital Poster Clinical target volume threshold for dose reduction from 60 Gy to 54 Gy in extensive glioblastoma Kurl Jamora 1,2 , Anthony Lausch 1,2 , Philip Ye 3 , ZhihuiAmy Liu 3 , Dana Keilty 1,2 , Derek Tsang 1,2 , Warren Mason 4 , David Shultz 1,2 , Normand Laperriere 1,2 , Barbara-Ann Millar 1,2 1 Department of Radiation Oncology, University of Toronto, Toronto, Canada. 2 Radiation Medicine Program, Princess Margaret Cancer Centre, University Health Network, Toronto, Canada. 3 Department of Biostatistics, Princess Margaret Cancer Centre, University Health Network, Toronto, Canada. 4 Department of Medicine, Divisions of Neurology and Department of Medical Oncology and Hematology, Toronto, Canada