ESTRO 2024 - Abstract Book

S745

Clinical - CNS

ESTRO 2024

SRS/FSRT is an effective option as an upfront treatment for BM arising from NSCLC in elderly patients, showing good OS without severe side effects. High GPA score and the administration of systemic therapy were associated with survival benefits.

Keywords: brain metastasis, lung carcinoma, radiosurgery

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Leptomeningeal metastases after postoperative stereotactic radiotherapy of brain metastases

Jeroen Crouzen 1 , Martijn Hakstege 1 , Anna L Petoukhova 2 , Mandy Kiderlen 1 , Noëlle CMG van der Voort van Zyp 1 , Elise van Schaik 1 , Mirjam E Mast 1 , Jaap D Zindler 1 1 Haaglanden Medical Center, Radiotherapy, Leidschendam, Netherlands. 2 Haaglanden Medical Center, Medical Physics, Leidschendam, Netherlands

Purpose/Objective:

Resection of brain metastases (BM) followed by stereotactic radiotherapy (SRT) is indicated for patients with a relatively favorable prognosis and with large symptomatic tumors. During BM resection, however, there is a risk of leptomeningeal metastases (LMM) seeding, due to intraoperative tumor spill. LMM is a fatal complication associated with high rates of neurologic morbidity and mortality. Furthermore, radionecrosis (RN) is a complication following high-dose radiation treatment, which can cause significant neurologic deficits. The purpose of this work was to analyze the incidence of LMM, RN and tumor recurrence to explore the need for studies on alternative treatment strategies.

Material/Methods:

Data of patients (n = 152, total of 285 BM) who had undergone postoperative SRT between 2010 and 2022 (18-25.5 Gy in 1 or 3 fractions) was retrospectively analyzed. Patients with a history of whole brain radiotherapy, cranial RT, or LMM were excluded. LMM was determined with either cerebrospinal fluid cytology or neuroimaging. Recurrence and RN were diagnosed on cerebral (perfusion-weighted) MR imaging scans (voxel size 0.9 x 0.9 x 0.9 mm3). Overall survival (OS) as well as time between SRT and LMM were analyzed. Actuarial incidence rates were estimated using the Kaplan-Meier method.

Results:

Median OS was 14 months (95% CI 11-17). Patient characteristics are shown in Table 1. Actuarial incidence of LMM was 13%, 15% and 23% after 1, 2 and 3 years, respectively (Figure 1). Median time to LMM was 6 months after postoperative SRT (range 2-30 months). Incidence of any RN was 22%, while symptomatic RN occurred in 14% of