MR imaging features of triple-negative breast cancers

Triple-negative (TN) breast cancers, which are associated with a more aggressive clinical course and poorer prognosis, often present with benign imaging features on mammography and ultrasound. The purpose of this study was to compare the magnetic resonance imaging features of TN breast cancers with estrogen (ER) and progesterone (PR) positive, human epidermal growth factor receptor (HER2) negative cancers. Retrospective review identified 140 patients with TN breast cancer who underwent a preoperative breast MRI between 2003 and 2008. Comparison was made to 181 patients with ER+/PR+/HER2- cancer. Breast MRIs were independently reviewed by two radiologists blinded to the pathology. Discrepancies were resolved by a third radiologist. TN cancers presented with a larger tumor size (p = 0.002), higher histologic grade (<0.001), and were more likely to be unifocal (p = 0.018) compared with ER+/PR+/HER2- tumors. MRI features associated with TN tumors included mass enhancement (p = 0.026), areas of intratumoral high T2 signal intensity (p < 0.001), lobulated shape (p < 0.001), rim enhancement (p < 0.001), and smooth margins (p = 0.005). Among the TN tumors with marked necrosis, 26% showed a large central acellular zone of necrosis.