Abstract
Background: Histologically normal breast fibroglandular tissue (FGT) enhances on contrast MRI and is called background parenchymal enhancement (BPE). Having high BPE is associated with an increased risk of breast cancer. We examined the relationship between MRI-FGT (a volumetric assessment of breast density) and BPE and breast cancer risk factors.Methods: This was a cross-sectional study of 419 women without breast cancer undergoing contrast-enhanced breast MRI. All women completed a questionnaire at the time of MRI. Prevalence ratios (PR) and 95% confidence intervals (CI) describing the relationship between breast cancer risk factors and BPE and MRI-FGT were generated using modified Poisson regression. Results: In multivariable adjusted models a positive association between BMI and BPE was observed, with a 5-unit increase in BMI associated with a 16% and 38% increase in prevalence of high BPE in pre- and post-menopausal women respectively. Conversely, a strong inverse relationship between BMI and MRI-FGT was observed in both pre- (PR=0.65, 95% CI 0.57, 0.76 per 5-unit increase of BMI) and post-menopausal (PR=0.67, 95% CI 0.57, 0.79, per 5-unit increase in BMI) women. Current use of oral contraceptives was associated with high BPE while use of preventive medication (e.g., tamoxifen) was associated with low BPE. Conclusion: This study identifies patient characteristics and exposures associated with BPE and MRI-FGT. BPE is a new imaging marker of breast cancer risk. The results of this study provide further support for the role of hormonal exposures on BPE.
A comparative study of pre- and post-menopausal breast cancer: Risk factors, presentation, characteristics and management
