Breast Density and Breast Cancer Risk Linkage
New BCSC study clarifies the association between breast density and cancer risk.
Confirmation of Link between Breast Density and Breast Cancer Risk
A new study in the American Journal of Epidemiology (February 2025), led by Jane Lange, PhD, clarifies the association between breast density and cancer risk. The findings show that dense breasts (BI-RADS categories 3 and 4) are linked to a 1.7-fold higher risk of breast cancer compared to non-dense breasts (BI-RADS categories 1 and 2).
The relationship between breast density and breast cancer risk is complicated by the fact that dense breast tissue reduces the effectiveness of screening mammograms, potentially delaying diagnosis. This issue, known as the 'masking problem,' has been recognized for decades. Less commonly acknowledged is that breast density may also influence screening rates, particularly in light of notification laws informing women of their increased risk—further impacting the timing of diagnosis.
This study presents the first rigorous modeling approach to assess how breast density influences the risk of disease onset—defined as the point when screening may first detect disease—independent of factors affecting the timing of diagnosis.
Key findings include:
In the BCSC, among women aged 40–54 undergoing their first digital mammogram between 2000 and 2018, mammography sensitivity was 73.7% for dense breasts and 87.7% for non-dense breasts.
Mammography attendance rates were 9% higher among women with dense breasts compared to those with non-dense breasts.
The relative risk of breast cancer diagnosis five years after the first screen was 1.8, compared to a relative risk of breast cancer onset of 1.7.
These findings support the current evidence base informing the Mammography Quality Standards Act (MQSA) that mandates that women be informed of the breast density status and the increased risk associated with dense breasts.
Lange JM, Gard CC, O'Meara ES, Miglioretti DL, Etzioni R. Breast density and risk of breast cancer: masking and detection bias. Am J Epidemiol. 2025 Feb 5;194(2):441-448. doi: 10.1093/aje/kwae245. PMID: 39098823; PMCID: PMC11815494. [link]
The full article can be found here
American Journal of Epidemiology
The accompanying editorial can be found here:
By: Jane Lange, PhD