Performance of enhancement on brain MRI for identifying HER2 overexpression in breast cancer brain metastases

Abstract

Purpose: To investigate whether enhancement on MRI could help identify HER2 overexpression in breast cancer brain metastases.

Methods: We derived a cohort of 38 histologically proven breast cancer brain metastases with preoperative contrast-enhanced brain MRI and HER2 fluorescent in-situ hybridization of the resected/biopsied brain specimens from 2018 to 2021. Enhancement of the lesions was measured and compared using t-tests. Receiver operating characteristic and logistic regression analyses were performed to evaluate the performance of MRI enhancement in identifying HER2 overexpression.

Results: The study cohort was comprised of 29 women with a mean age of 55 years (range: 31-81 years) with a total of 38 distinct lesions. The HER2-positive subcohort was comprised of 17 patients, while the HER2-negative subcohort was comprised of 13 patients. The percent signal intensity change (PSIC) of HER2-positive breast cancer brain metastases was significantly greater than that of HER2-negative lesions (310 v. 153, P = 0.002). The PSIC differentiated HER2-positive lesions from HER2-negative lesions with an area under the curve of 0.88 (P < 0.001). In a model controlling for lesion size, lesion location, tumor grade, patient age, scanner magnetic field strength, and contrast agent, the PSIC had an accuracy of 92% (35/38), sensitivity of 96% (23/24), and specificity of 86% (12/14) in differentiating HER2-positive lesions from HER2-negative lesions.

Conclusion: Enhancement on MRI may assist in identifying HER2 overexpression in breast cancer brain metastases, if validated prospectively.

Keywords: Brain metastases; Breast cancer; Magnetic resonance imaging.