ESTRO 2024 - Abstract Book

S755

Clinical - CNS

ESTRO 2024

1 CHUV, Radiation Oncology, Lausanne, Switzerland. 2 CHUV, Oncology, Lausanne, Switzerland. 3 CHUV, Institute of Radiation Physics, Lausanne, Switzerland. 4 CHUV, Radiology, Lausanne, Switzerland. 5 CHUV, Neurosurgery, Lausanne, Switzerland

Purpose/Objective:

Multiple brain metastases (BM) is a frequent and a life-threatening cancer related complication. Whole-Brain radiotherapy (WBRT) has historically been considered as a standard treatment for patients with multiple BM.

Objective : To evaluate the outcome and prognosis factors in patients with at least 10 lesions at the time of BM diagnosis and treated by stereotactic radiotherapy (SRT).

Material/Methods:

This is a monocentric cohort of patients treated by SRT and followed by brain MRI every two months. Subsequent SRT could be delivered in case of new BM during follow-up.

The main endpoints were local control rate (LCR), overall survival (OS) and strategy success rate (SSR). SSR is a composite endpoint that corresponds to the proportion of patients not requiring WBRT and not dead from a neurological progression. Acute and late toxicity were evaluated.

Results:

Seventy patients were included from October 2014 to January 2019, the most frequent primary was non-small-cell lung cancer (N=36, 51.4%) and in good condition (PS 0-1: 80.0%). A total number of 1174 BM were treated at first treatment, corresponding to a median number of 14 metastases per patient (10-64). Patients were mostly treated with a single fraction of 20 Gy and the mean brain dose (MBD) was 3.8 Gy. Median follow-up was 18.8 months. At 1 year, OS was 62.3% (50.0-74.6) with a median OS of 19.2 months (3.6-55.1), and SSR was 77.8 % (66.1-89.5). A cumulative number of 1537 BM were treated overtime, corresponding to a median cumulative number of 16 (10 105) BM per patient, with a MBD of 4.9 Gy. At 1-year, the LCR was 97.3% (96.4-98.2) with a cumulative incidence of radio-necrosis of 2.1 % (1.0- 3.1) per lesion. Three patients (4.3%) presented Grade 2 toxicity with no Grade ≥3 toxicity. The was no influence of the number of treated BM neither than the treatment volume over OS or SSR.

Conclusion:

This is a unique cohort of patients with ≥10 BM at first SRT. SRT was highly efficient to control the BM, with minimal side effects. In this setting, a SRT treatment for multiple BM should be proposed regardless the number of BM.

Keywords: : Brain metastases, stereotactic radiotherapy,