ESTRO 2023 - Abstract Book

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ESTRO 2023

age was 64 (41-85) years. Primary tumor was lung in 10 pts, breast in 7 pts, melanoma in 4 pts, parotids in one patient and one patients had lung and breast cancer simultaneously. Seven pts were previously treated with Whole Brain Radiotherapy (WBRT). Gross tumor volume (GTV) and organs at risk (OAR) were defined on a contrast-enhanced T1-weighted MRI fused to simulation-computed tomography (CT). A 1 mm margin was added to GTV to define Planning target volume (PTV). For 27 out of 28 treatments, steroid therapy was administrated as precautional therapy. Post-treatment MRI scans were used to assess local control (LC) and disease progression (PD) according to the Response Evaluation Criteria in Solid Tumors (RECIST) scale. Acute toxicity was assessed according to the CTCAE v5.0. Survival curves were calculated from the date of treatment by using the Kaplan-Meier (KM) method. Results Median number of brain metastases/patient was 15 (10-46). Median GTV 4.78 (0.46-22.33) cc, and median PTV 10.01 (1.57 32.99) cc. Median prescribed dose was 30 (24-37.5) Gy, at the 77 (66-80) % median isodose, in a median of 3 (1-5) fractions, delivered in consecutive days. With a median follow up of 4.13 (0.5-27.04) months, 19 pts were found dead. Acute toxicity was as follows: 3 pts presented G1 dizziness and one patient G2 dizziness, 2 pts G1 headache, 1 patient G1 nausea, 1 patient G1 hemiparesis (weakness), and 1 patient G1 dysgeusia. No patient presented radionecrosis. Overall Survival (OS) at 6-, and 12-months was 40.9%, and 15.3%, respectively. Six- and 12-month Local Relapse Free Survival (LRFS) was 90.4%, and 65.9%, respectively (see Fig.1). Intracranial Relapse Free Survival (IRFS) at six and 12-months were 50.7%, and 25.3%, respectively (See Fig.2).

Figure 1. Local Relapse Free Survival.

Figure 2. Intracranial Relapse Free Survival.

Conclusion SRS/SRT can be considered a feasible treatment strategy with a good toxicity profile and excellent local control rates in pts with more than 10 brain metastases. Based on our results, careful patient selection is required.

PO-1112 Outcomes after Stereotactic Radiosurgery for Brain Metastases from Gastro-intestinal malignancies

P. Sharma 1 , G. Rangaswamy 1 , J. Nicholson 1 , J. Waldron 2 , C. Skourou 2 , M. Dunne 3 , N. El Beltagi 1 , C. Faul 1 , D. Fitzpatrick 1

1 St Luke’s Radiation Oncology Network, Radiation Oncology, Dublin, Ireland; 2 St Luke’s Radiation Oncology Network, Medical Physics, Dublin, Ireland; 3 St Luke’s Radiation Oncology Network, Clinical Trials Unit, Dublin, Ireland Purpose or Objective Brain metastases (BM) occur in <4% of all tumours from the gastro-intestinal (GI) tract. The incidence is increasing with more effective systemic treatments and prolonged survival. Whilst whole brain radiotherapy (WBRT) plays an integral part in the management, stereotactic radiosurgery (SRS) is an established treatment modality in both the definitive and adjuvant setting. We present our institutional experience of treating BM from GI malignancies with SRS. Materials and Methods We retrospectively analysed data on patients referred for SRS for BM from GI malignancies between June 2015 and October 2021. Medical records and dosimetry data on these patients were reviewed. We obtained data on patient demographics, tumour characteristics and presence of extra-cranial metastases. SRS was planned using the iPlan software and follow-up neuro-imaging evaluating treatment response was reviewed. The Kaplan-Meier method was used to estimate survival times for individual patients from the day SRS was completed to the date of last follow up or death.