Proactive Brain Screening Using Contrast-Enhanced Brain CT Scans in HER2+ Metastatic Breast Cancer

Purpose: According to recent EANO-ESMO guidelines, proactive brain imaging can be considered in asymptomatic patients with HER2+ metastatic breast cancer (mBC) because of high risk of developing brain metastases. However, optimal imaging modality and timing remain unclear. We retrospectively assessed the impact of contrast-enhanced CT screening on symptomatic brain metastases in patients with HER2+ mBC. Experimental design: Consecutive patients newly diagnosed with HER2+ mBC treated with trastuzumab-pertuzumab plus taxane (2014-2024) were retrospectively identified. Brain screening was defined as at least one contrast-enhanced brain CT scan per year without neurologic symptoms during the first 2 years after diagnosis. Results: Among 148 identified patients, 73 underwent brain screening and 75 did not. The median number of annual brain CT scans during the first 2 years was 2.0 (IQR, 1.2-2.5) and 0.0 (IQR, 0-0.5) in the screening and nonscreening groups, respectively. Thirty (20.3%) patients developed brain metastases during the first 2 years. The cumulative brain metastasis incidence was significantly higher in patients undergoing screening (30.6% vs. 12.3%, Gray's P = 0.004), but symptomatic brain metastases were significantly lower in patients undergoing screening (0% vs. 9.5%, Gray's P = 0.012). Patients undergoing screening had better preserved performance status at brain metastasis diagnosis (P = 0.002) and a numerical trend toward fewer brain metastases (P = 0.057). Treatment patterns after brain metastasis diagnosis were similar, although whole-brain radiotherapy was used less often in the screening group (14.3% vs. 44.4%, P = 0.073). Conclusions: Brain screening with CT scans was associated with fewer symptomatic brain metastases and better performance status at brain metastasis diagnosis, supporting proactive imaging in HER2+ mBC. Prospective studies are warranted to define optimal timing and imaging modalities.