Brain Radiotherapy Combined with Targeted Therapy for HER2-Positive Breast Cancer Patients with Brain Metastases

Background: Research on the sequencing of brain radiotherapy and targeted chemotherapy after brain metastasis (BM) in HER2positive breast cancer patients is limited and inconclusive. This study investigated the efficacy of sequential delivery of radiotherapy and targeted therapy in patients with human epidermal growth factor receptor 2 (HER2)-positive breast cancer with BM. Methods: Fifty-seven patients were categorized into two groups: the targeted-radiotherapy group (receiving 2-8 cycles of anti-HER2targeted therapy followed by radiotherapy after BM) and the radiotherapy-targeted group (undergoing radiotherapy first, followed by regular anti-HER2-targeted therapy). The study endpoints were intracranial progression-free survival (iPFS) and overall survival. Factors associated with intracranial progression and mortality were assessed by univariate and multivariate Cox proportional hazards analysis. Results: Patients in the radiotherapy-targeted group had better iPFS (P < 0.001), while there was no significant difference in overall survival between the two groups (P = 0.145). Multivariate Cox analysis showed that different sequential treatment groups were independent prognostic factors for iPFS. In patients with a modified breast graded prognostic assessment score of 3.5-4.0, the median survival time was 26 months in the radiotherapy-targeted group and 22 months in the targeted-radiotherapy group (P = 0.019). Conclusion: Overall, radiotherapy followed by targeted therapy may improve survival in HER2-positive breast cancer patients with BM, particularly in those with a modified breast graded prognostic assessment score of 3.5-4.0.