Diagnostic Performance of Magnetic Resonance Imaging for Assessing Tumor Response in Patients With HER2-Negative Breast Cancer Receiving Neoadjuvant Chemotherapy is Associated With Molecular Biomarker Profile

Micro-Abstract The influence of hormone receptors (HRs) and the Ki-67 proliferation marker in the accuracy of measuring tumor size by magnetic resonance imaging (MRI) after chemotherapy was investigated in 54 patients with HER2-negative (HER2− ) breast cancer. The accuracy was higher in HR-negative (HR− ) tumors than in HR-positive (HR+ ) tumors and was also higher in tumors with ≥ 40% Ki-67 staining than in those with < 40% Ki-67 staining, suggesting that the accuracy of MRI is better in more aggressive phenotypes.