RADI-44. MANAGEMENT OF MULTIPLE BRAIN METASTASES BY STAGED SRS FOCUSING ON UTMOST RISK LESIONS

BACKGROUND: Patients with multiple large brain metastases (LBMs) are subject to cause intracranial hypertension, which remains a clinical difficulty so far. The present study is to investigate whether staged stereotactic radiosurgery (SRS) is a feasible solution to improve clinical symptoms and life quality in palliative management. METHODS: Patients with brain metastases treated between 1 January 2016 and 30 March 2019 were retrospectively studied. The patients inclusion criteria included were: 1) metastatic lesions ≥ 3; 2) tumor lesions with a supratentorial invasion ≥ 3 cm or a subtentorial invasion ≥ 2 cm; 3) with neurological impairment or with a high risk for intracranial hypertension. The first stage of SRS dose regimens for utmost risk supratentorial lesions were 20-24Gy within 2-fractions (fx); whereas 24Gy/3-fx for subtentorial lesions. For the 2nd stage, the rest metastatic lesions with relatively lower risk were treated with 16-18Gy/1-fx one week after that. RESULTS: A total of 30 patients were enrolled included in this study. The neurological symptoms were significantly relieved following 1st stage of SRS, with a median period of 3 days (2–14 days). 13 out of 30 patients were randomly selected for MR imaging two weeks after SRS. It suggested that 84.6% (11/13) of the patients were observed with a clear reduction of tumor volume. The median reduced diameter was 0.38 (0.17–0.83) cm and a median volume reduction was 3.22 (0.01–9.08) mm3. According to RANO-BM, the objective remission rate of utmost risk lesions was 100%, whereas the less critical lesions was 95.16% (59/62). One patient (3.33%) was identified with acute adverse reaction (> grade 3). CONCLUSIONS: Staged SRS with a priority for utmost risk lesions was indicated to be an effective approach for multiple large brain metastases. Further prospective study is highly warranted.