ESTRO meets Asia 2024 - Abstract Book

S92

Interdisciplinary – CNS

ESTRO meets Asia 2024

18

Digital Poster

efficacy and safety of local irradiation of brain metastases: a single-center retrospective study

Qian Bi, Xin Lian, Fuquan Zhang

Department of Radiation Oncology, Peking Union Medical College Hospital, Chinese Academy of Medical Science and Peking Union Medical College, Beijing, China

Purpose/Objective:

To investigate the outcomes of local irradiation brain metastases in patients with brain metastases and analyze the prognostic impact of some factors.

Material/Methods:

This single-arm retrospective study analyzed patients with brain metastases treated with local irradiation brain metastases (prescription dose range of 20-60 Gy/2-25 fractions, most commonly delivered as 30 Gy/5 fractions, with a BED range of 28-100.8 Gy) at Peking Union Medical College Hospital between September 2015 and December 2021, with a total of 157 metastases. The prescription dose was divided into 3 groups based on the number of fractions: 42 patients in the hypofraction group (up to 5 fractions and median BED value of 51.3 Gy), 18 patients in the moderately hypofraction group (6-9 fractions and median BED value 60Gy), and 21 patients in the conventionally fraction group (more than 10 fractions and median BED value 75Gy). The primary endpoint was intracranial progression free survival (iPFS). Secondary endpoints included overall survival (OS), intracranial new foci, and tumor control. Kaplan-Meier method was utilized to depict and estimate iPFS, OS, intracranial new foci, and tumor control. The Cox regression analysis was performed to assess the association between relevant factors and outcomes.

Results:

A total of 81 patients were included, and the median iPFS was 9.4 (95% CI: 6.5-12.3) months. The median value of OS was 22.5 (95% CI: 13.9-31.1) months. Median local control time was not reached (NR). Median new intracranial foci time was 11.2 (95% CI: 7.2-15.3) months. The median local control time was NR in the hypofraction group, moderately hypofraction group, and conventionally fraction group, respectively. No differences in iPFS and local control were observed among the three modes of fraction. Patients' receipt of targeted therapy throughout the course of brain metastases was associated with local control (HR=7.9, 95% CI: 2.1-29.5, P=0.002) and iPFS (HR=2.9, 95% CI: 1.1-6.8, P=0.015). Tumor pathology type was strongly associated with iPFS (HR=0.4, 95% CI: 0.1-0.9, P=0.037).

Conclusion:

iPFS, survival, local control, and intracranial new foci in patients with brain metastases after treatment with local irradiation of brain metastases were acceptable. Patients' receipt of targeted therapy and tumor pathology type may be associated with iPFS and local control of the tumor.