Efficacy Analysis of Stereotactic Radiosurgery Combined with Multicycle Low-dose Bevacizumab in the Treatment of Brain Metastases Located in the Motor Cortex

Objective: This study aims to preliminarily investigate the efficacy and safety of stereotactic radiosurgery (SRS) combined with multiple cycles of low-dose bevacizumab (BEV) in the treatment of brain metastases located in the motor cortex. Methods: A retrospective analysis was performed on the relevant data of 40 patients with large brain metastases (LBMs) located in the motor cortex and with diameters between 2.5 cm and 3.5 cm. These patients underwent SRS at the Stereotactic Radiosurgery Center of Zhongshan Hospital, Xiamen University from January 2020 to October 2024. All patients received SRS. Patients were categorized into the SRS + BEV group and the SRS-only group on the basis of whether BEV was administered. Follow-up cranial magnetic resonance imaging (MRI) was performed to assess changes in peritumoral brain edema (PTBE) and tumor volume. Changes in ipsilateral muscle strength and functional activity before and after treatment were also recorded. Comparative analyses were conducted between the SRS + BEV group and the SRS-only group regarding changes in PTBE, tumor volume reduction, improvements in muscle strength, and functional status. Results: In the SRS + BEV group, there was a statistically significant difference in the edema index (EI) values before and after radiotherapy (p < 0.001), with lower EI values observed posttreatment. In contrast, no statistically significant change was found in the SRS-only group ( p = 0.451). The degree of volume reduction was significantly greater in the SRS + BEV group than in the SRS-only group ( p = 0.045). Compared with the SRS-only group the SRS+BEV group demonstrated significantly greater improvement in muscle strength (p = 0.015). Similarly, compared with the SRS-only group, the SRS + BEV group presented a more pronounced enhancement in functional status (p = 0.039). Conclusion: SRS combined with multiple cycles of low-dose bevacizumab can significantly reduce the severity of PTBE following SRS in patients with brain metastases located in the motor cortex. Furthermore, this combination therapy contributes to a redution in tumor volume , improvement in muscle strength, and improvement in patients' quality of life and treatment outcomes.