ESTRO 2023 - Abstract Book

S923

Digital Posters

ESTRO 2023

In this single institutional retrospective review, we identified patients diagnosed with brain metastases of varying histologies, who were treated with radiotherapy and subsequently developed RICE. Patient demographic and clinical data, radiation-, cancer-, and RICE-treatment, radiological results, toxicity, and oncological outcomes were reviewed in detail. Results A total of 95 patients with a median follow-up of 28.8 months were identified. Most common primary tumor entity was lung cancer (n= 50, 52.6%), followed by breast cancer (n=16; 16.8%) and melanoma (n=12, 12.6%). All patients were treated with RT for brain metastases with either whole-brain RT (WBRT) or stereotactic radiosurgery. First RT treatment included stereotactic RT for 81 patients (85.3%), comprised with a median total dose of 20 Gy in one fraction in 55 patients and fractionated treatment in 26 patients. The remaining 14 patients (14.7%) received WBRT with a median dose of 30 Gy in 10 fractions. A total of 27 patients received re-irradiation treatment with WBRT (n=6,) single fraction radiosurgery (n=16) and fractionated radiosurgery (n=5) for the same lesion. Ultimately, RICE appeared after a median time of 8.0 months after first RT treatment and after 6.4 months after re irradiation. Correlations of treatment RT plans confirmed RICE localization to the previously treated lesion. Bevacizumab achieved an improvement of clinical symptoms and imaging features in 65.9% and 75.6% of cases, respectively, both significantly superior compared to treatment with corticosteroids. Bevacizumab further significantly prolonged RICE progression-free survival to a median of 5.6 months. Recurrence of RICE after initially improved or stable imaging occurred in 63.1% of cases, significantly more often in patients after re-irradiation and was associated with high mortality of 36.6% after the diagnosis of flare-up. Response of recurrence significantly depended on the applied treatment and multiple courses of bevacizumab achieved good response. Conclusion Our results suggest that bevacizumab is superior in achieving short-term imaging and symptom improvement of RICE and prolongs the progression-free time compared to corticosteroids alone. Long-term RICE flare-up rates after bevacizumab discontinuation are high, but repeated treatments achieved effective symptomatic control. Purpose or Objective Optic nerve sheath meningiomas (ONSMs) are rare benign neoplasms of the orbita and occur primarily in adults with a peak incidence in the 45 to 55 years old age group. The triad of progressive visual loss, optic disc pallor, and retinochoroidal shunting is typical for ONSM. The triad occurs relatively late and is seen in 25-33% of the patients. A ‘tram tracking sign’ can be seen on magnetic resonance imaging and is suggestive for ONSM. Invasion into surrounding orbital structures is rare, contributing to an excellent prognosis for life. The mass effect leads to compression of the optic nerve and deterioration of the optic nerve function with loss of visual acuity (VA), and diminished visual fields. Radiotherapy has proven to be the only treatment modality allowing stabilization of the tumor and even improvement of VA in 25-80% of the patients. Acute radiotherapy induced ocular toxicities (conjunctivitis, dry eye) are well known, but the long-term ocular toxicity retinal vasculopathy, which may contribute significantly to a deterioration of patient’s visual function and quality of life (QoL), is less known. We primarily aimed to evaluate the visual outcome (VA, visual field (VF), and color vision (CV)) after radiotherapy), and secondary the occurrence of retinal vasculopathy through qualitative and quantitative analysis and study how these interfere with QoL. Materials and Methods Adult patients who had fractionated stereotactic radiotherapy (54Gy total dose given in 30 fractions of 1.8Gy) for ONSM with a follow-up of at least 18 months were invited for a detailed ophthalmological assessment. VA, VF, and CV were tested which together represented the visual outcome (i.e. our primary parameter). The secondary outcome parameter was the occurrence of retinal vasculopathy. Ultra-widefield fluorescein angiography (UWFA) was performed for qualitative evaluation of the superficial retinal vasculature and optical coherence tomography angiography for quantitative evaluation of the retinal microvasculature. Additionally, we analyzed how these interfere with QoL through ‘the Graves’ ophthalmopathy QoL questionnaire. Results Eight patients were included. VA improvement occurred in 13%, stabilization in 13%, and deterioration in 74%. VF deterioration was observed in 75% and stabilization in 25%. CF improvement occurred in 12%, stabilization in 63%, and improvement in 25%. (Table 1) Capillary nonperfusion and microaneurysms were observed on UWFA indicating retinal vasculopathy in two patients (Figure 1). In patients with exophthalmos induced by the tumor, 36% felt their condition had influenced their self-confidence. PO-1153 Visual outcome after fractionated stereotactic radiotherapy for optic nerve sheath meningioma B. Kinaci-Tas 1 1 Leiden University Medical Centre, Radiotherapy, Leiden, The Netherlands