ESTRO 2023 - Abstract Book

S894

Digital Posters

ESTRO 2023

HER2 over-expression is associated with an higher incidence of cerebellum disease, with better intracranial control and OS, in particular for limited BM treated with stereotactic radiation therapy. HER2 status should be considered in radiation therapy management of breast cancer brain metastases.

PO-1118 Brain directed therapy followed by systemic treatment in metastatic renal cell carcinoma

M. Zarroug 1 , A. Shaheen 1 , A. Mohammed 1 , M. Elgendy 1 , A. Burns 1 , M. AlHilali 1 , M. Vanderputten 1 , A. Azzabi 1 , R. Chandler 1 , J. Frew 1 , H. Hayhurst 1 , M. Jackson 1 , I. Pedley 1 , R. Pearson 1 , X. Jiang 1

1 The Newcastle upon Tyne NHS Foundation Trust, Northern Centre for Cancer Care, Newcastle upon Tyne, United Kingdom

Purpose or Objective To assess the impact of brain directed therapy (BDT) in patients with metastatic renal cell carcinoma (mRCC) with brain metastases (BM), who have received stereotactic radiosurgery (SRS) – with or without surgery, and systemic anti-cancer therapy (SACT) in the Northern Centre for Cancer Care (NCCC), United Kingdom (UK). Materials and Methods This is a retrospective analysis of patients diagnosed with mRCC between January 2018 and July 2022 who then developed brain metastases and received brain directed therapy. Data was extracted from the chemotherapy register and cross referenced with the radiotherapy database and medical electronic records in the NCCC, UK. Results We identified n=28 patients (16.2 %) out of 172 who had developed brain metastases during the period. IMDC favourable, intermediate, and poor risks distribution were 9, 13, 6 respectively. Median age was 65 (54 – 77). 19 (67.8%) patients were male and 9 (38.3%) were female. Twenty-six (15.1%) were symptomatic, and 2 (1.1%) were asymptomatic. 10 (35.7%) were SACT naïve, 10 (35.7%) were on first line treatment with tyrosine kinase inhibitor (TKI), 1 (3.6%) were on first line immunotherapy (IO) and 7 (25.0%) had multiple lines of treatment including TKI and IO. Twenty (71.4%) patients received BDT (16 (57.1%) received radiotherapy, 2 (7.1%) received SACT alone and 2 (7.1%) had surgery alone). Eight (28.5%) were placed on best supportive care (BSC) with no further SACT. Of the 16 patients (57.1 %) who received radiotherapy, 3 (10%) received whole brain radiotherapy (WBRT), 13 (6.0%) received SRS using VMAT technique, with doses ranging between 15 and 25 Gy in 1 to 5 fractions. Ten out of the 13 patients had SRS to the surgical cavity, while 2 received primary SRS and 1 patient had surgery to the largest metastasis followed by SRS to the surgical cavity and the other non-resected lesions. The average treated volume was 13.887cm3 (0.325 - 34.393), the maximum number of lesions treated was 3. Ten patients (35.7%) went on to have further SACT post SRS with 4 of the 10 patients receiving 2 lines of SACT. In SRS group (n=13), 7 relapsed within the brain, none of which relapsed within the radiotherapy fields. Of those relapsed patients, 2 received further SRS and 1 patient underwent surgery. Patients relapsed within 4 to 19 months, with 57.1% relapsing within 4 to 5 months and 42.9% relapsing after more than 9 months. Median overall survival (OS) from first treatment (BDT or SACT) in patients with brain metastasis vs without was 6.9 vs 34 months respectively (P value = 0.0005, HR =2.23, 95% CI 1.20 -4.13).

Conclusion BM is common in mRCC and symptomatic detection is often late leading to BSC only. We suggest regularly imaging surveillance for early detection and BDT. SRS is highly effective in local control of treated lesions however relapse outside SRS field is common. BM is a poor prognostic indicator despite BDT and SACT consistent with literature. Further study into pattern of failure and best sequence of SACT on survival is needed.

PO-1119 Mimicking neoadjuvant stereotactic radiosurgery for resection cavities of brain metastases

C. Senger 1 , M. Nachbar 1 , N. Soffried 2 , B. Bodnar 2 , A. Janas 3 , G. Kalinauskaite 4 , A. Kluge 5 , D. Schultz 6 , A. Conti 7 , D. Kaul 8,9 , D. Zips 5 , P. Vajkoczy 10 , G. Acker 11,10,12 1 Charité - Universitätsmedizin Berlin , Department of Radiation Oncology and Radiotherapy, Berlin, Germany; 2 Charité - Universitätsmedizin Berlin , Department of Radiation Oncology and Radiotherapy, Berlin , Germany; 3 Charité - Universitätsmedizin Berlin , Department of Neurosurgery, Berlin, Germany; 4 Charité - Berlin Universitätsmedizin,