Evaluation of Background Parenchymal Enhancement Correlates with Lifetime Breast Cancer Risk

Overview

This study quantitatively assessed background parenchymal enhancement (BPE) on breast MRI in women with varying lifetime breast cancer risk, including BRCA mutation carriers. Findings indicate that BPE levels differ among risk groups and are influenced by clinical factors such as age, menopausal status, and breast density.

Background

Breast cancer is a leading cause of cancer-related mortality among women, with mammography as the standard screening tool. However, mammography sensitivity is reduced in women with dense breast tissue, prompting recommendations for supplemental MRI screening in women with a lifetime breast cancer risk above 20%. Background parenchymal enhancement (BPE) on contrast-enhanced MRI reflects fibroglandular tissue vascularity and may correlate with breast cancer risk, though prior studies have shown conflicting results. Understanding BPE's relationship with genetic risk factors like BRCA mutations and classical risk models could improve individualized screening strategies.

Data Highlights

The study retrospectively reviewed 4859 contrast-enhanced bilateral breast MRI exams from 2017 to 2019, excluding patients with prior breast cancer, mastectomy, unknown risk scores, or recent tamoxifen use. Eligible women were stratified into three groups: nonhigh-risk (<20% lifetime risk), high-risk non-BRCA (≥20% risk without BRCA mutation), and BRCA mutation carriers. MRI scans were performed on a 3-T scanner with standardized protocols, and BPE was quantified using a fully automated deep learning segmentation method. Clinical variables collected included age, BMI, menopausal status, hormonal therapy history, breast density, and genetic test results.

Key Findings

• Quantitative BPE measurements differed significantly between women with high lifetime breast cancer risk and those with lower risk.
• BRCA1/2 mutation carriers exhibited distinct BPE characteristics compared to noncarriers, though previous studies have reported conflicting results.
• BPE levels were influenced by hormonal factors such as menopausal status and menstrual cycle timing, as well as breast density.
• Adjusting for clinical factors reduced but did not eliminate differences in BPE between risk groups, suggesting an independent association with breast cancer risk.
• Automated quantitative assessment of BPE reduces variability inherent in radiologist-assigned categories, improving reproducibility.

Clinical Implications

Quantitative BPE assessment on breast MRI may serve as an adjunct biomarker to refine breast cancer risk stratification beyond traditional models and genetic testing. Incorporating BPE measurements could help tailor screening protocols, particularly in women with dense breasts or genetic predispositions. Awareness of hormonal influences on BPE is important when scheduling MRI to optimize risk assessment accuracy.

Conclusion

This study supports the potential role of quantitative BPE as a physiological correlate of lifetime breast cancer risk, including in BRCA mutation carriers. Further research may validate BPE as a useful imaging biomarker to enhance personalized breast cancer screening strategies.

References

1. American Cancer Society -- Breast Cancer Facts & Figures
2. Goodburn et al. 2022 -- BPE Differences in BRCA Mutation Carriers
3. Tyrer-Cuzick Model -- Breast Cancer Risk Assessment