Background parenchymal enhancement on breast MRI and mammographic breast density: correlation with tumour characteristics

Aim To investigate the relationship between mammographic breast density (MGD) and background parenchymal enhancement (BPE) at breast MRI and histopathological features of invasive breast cancers. Materials and methods A total of 178 women with unilateral invasive breast cancer who preoperatively underwent mammography and breast MRI were included in the study. Two radiologists rated MGD and BPE according to BI-RADS criteria in consensus. The relationship between MGD and BPE was investigated, and compared with histopathological features of invasive breast cancers according to the level of MGD and BPE. Results At MRI, there is no significant difference in the distribution of MGD and BPE of the contralateral breast in women with invasive breast cancer according to menopausal status ( p =0.226, 0.384). Women with high MGD (>50% glandular) were more likely to have oestrogen-receptor (ER)-positive breast cancer ( p =0.045) and progesterone receptor (PR)-positive breast cancer ( p =0.020). With regard to BPE, PR positivity correlated with moderate or marked BPE with borderline significance ( p =0.054). Multivariate logistic regression analyses revealed that women with high MGD were less likely to have triple-negative (i.e., a cancer that is ER negative, PR negative, and human epidermal growth factor receptor type 2 [HER2] negative) breast cancer compared with ER (+)/HER2 (−) cancer (OR=0.231, 95% CI: 0.070, 0.760; p =0.016). No association between the histological tumour characteristics and BPE was observed. Conclusion In women with invasive breast cancer, high MGD is associated with ER positivity of the invasive breast cancer. However, at MRI, BPE of the contralateral breast seems to be independent of tumour characteristics.