Final data set as excel sheet.

Background
HER2-positive breast cancer is leading to aggressive tumor growth and a higher risk of metastasis, particularly to the central nervous system (CNS). Routine brain imaging for asymptomatic HER2-positive patients is debated, with no current consensus; Given the severe clinical implications of brain metastases, further research is needed to determine the cost-effectiveness and clinical utility of routine imaging for high-risk patients to improve outcomes and inform targeted screening protocols.
Methods
This retrospective, monocentric study at the General Hospital of Vienna (AKH Wien) examined female HER2-positive breast cancer patients at first diagnosis to assess brain metastasis from January 2019 to February 2024. The study included patients with asymptomatic confirmed HER2 positive breast cancer. Data were collected through comprehensive medical records and brain imaging with MRI.
Results
Among 110 female patients meeting the inclusion criteria, 4 (3.6%) were diagnosed with brain metastases. Ki67 showed a marginal association with brain metastasis (p = 0.054), and tumor grade was a significant predictor, with intermediate differentiated tumors (G2 vs. G3) associated with a higher risk of brain metastases (p = 0.041) and brain metases are correlating with the axillary lymphnode status and the tumor sizeAlso, the absence of positive Östrogen and Progesteron receptors is a predictor in upcoming brain metastases (p < 0.001). Other factors like age were not significantly associated.
Conclusion
This study found limited benefit in routine MRI for detecting asymptomatic brain metastases in HER2-positive breast cancer, given the low prevalence (3.6%). A targeted imaging approach for high-risk patients, like those with the absence of Hormon receptors and higher stage tumors, may be effective.