This BCRF-supported research explores how having both a family history of breast cancer and dense breast tissue may interact to raise risk, offering vital insights for early detection and prevention.
We know that breast cancer risk is elevated in women who have a family history of breast cancer and those with dense breasts, but few studies have examined whether these strong risk factors are associated.
A new BCRF-supported study has addressed this question and provided new insights—particularly for premenopausal women.
Key takeaways:
- Women with a family history of breast cancer are more likely to have dense breast tissue.
- Dense breasts make mammograms more challenging to interpret and may increase cancer risk.
- Understanding both factors helps doctors personalise screening plans.
Understanding family history of breast cancer and breast density
Researchers have long recognized that understanding the factors that increase an individual’s risk for breast cancer is key to personalizing risk prediction and prevention.
Studies have found that women with a family history of breast cancer (in a close relative such as a parent or sibling) have a two- to four-times-greater risk of the disease themselves.
Breast density—the ratio of connective and glandular tissue to fatty tissue—is also associated with an increased risk; women with more than 75 percent dense breast area have a four-to-six-fold increase in breast cancer risk compared to women with less than five percent dense area (mostly fatty tissue).
This increased risk is due, in part, to the difficulty in detecting suspicious lesions that may be masked by dense tissue and missed by mammograms. Studies have also shown that the genes associated with having dense breasts are the same as those for developing breast cancer, suggesting that the increased risk of breast cancer in women with dense breasts is multi-factorial.
Why studying both family history and breast density together is important
Researchers have long understood that a family history of breast cancer and dense breast tissue are each strong—yet independent—risk factors. Studying them together, however, may provide a clearer picture of breast cancer risk, especially in younger or premenopausal women.
Family history of breast cancer may point to inherited genetic mutations or shared environmental factors that increase risk, while having dense breasts makes interpretation ofstandard imaging more difficult. By examining how these two factors interact, researchers and clinicians can better refine risk models and move toward more personalized screening recommendations tailored to each individual’s unique risk profile.
Designing a study to tackle two big questions
In this study, BCRF investigator Dr. Graham Colditz and his colleagues tested the hypothesis that a family history of breast cancer is associated with a higher risk of having dense breasts and focused on premenopausal women. Menopausal status was a particularly important aspect of the study since breast density decreases with age due to hormonal changes during menopause, and premenopausal women tend to have denser breasts than postmenopausal women.
“These two factors have strong associations with breast cancer risk but surprisingly, there is limited data on how they are both related—especially in premenopausal women and Black women,” Dr. Colditz said.
The team’s study provided several advantages over prior reports. The dataset contained over 14,000 premenopausal women to statistically improve interpretation of the results, and the study population was racially diverse, reflecting the population distribution in the greater St. Louis area, where the study took place. Additionally, researchers used two methods of measuring breast density (volumetric and mammographic) to confirm that results were consistent and independent of the method. In fact, this study was the first to assess the connection between family history and breast density using volumetric methods—those that provide a more objective assessment of breast tissue volume by using artificial intelligence and mathematical modeling to digitally analyze mammograms.
Key results and implications for premenopausal women
Dr. Colditz and his team demonstrated that their hypothesis was correct: In premenopausal women, having a family history of breast cancer was, in fact, associated with having dense breasts. Both Black and white women showed similar results. Furthermore, a strong and consistent association was found regardless of whether breast density was measured by qualitative (mammographic) or quantitative (volumetric) means.
These results highlight the importance of knowing your family history and, for premenopausal women with a family history, talking with your doctor about starting breast cancer screening at an earlier age to detect the disease sooner.
And, pulling back the lens, these results also underscore the greater need to move toward more personalized risk-based screening that is tailored to each person’s risk rather than age.
“Our study strongly reinforces the message that women who have a family history of breast cancer, irrespective of race, should start annual screening mammogram early,” Dr. Colditz said. “And we are still exploring ways to build on these findings but certainly want to better understand how this can help us work toward better prevention approaches for premenopausal breast cancer.”
What discoveries mean for screening and prevention
These findings reinforce the need for personalized, risk-based breast cancer screening. For women—particularly those who are premenopausal—with both a family history of breast cancer and dense breast tissue, early and proactive screening may be critical. Because dense tissue can obscure tumors on mammograms, healthcare providers may recommend additional imaging, such as a breast ultrasound or MRI, to enhance detection. Sharing your whole family history—both your mother’s and father’s side—with your provider can help determine when to start screening and which tools are recommended for you.
Research like this, supported by BCRF, continues to advance more tailored prevention and early-detection strategies that can save lives.
Help accelerate research that saves lives. Fundraise with BCRF to support breakthroughs that empower women to understand and manage their breast cancer risk.
Frequently asked questions about family history of breast cancer
A family history typically means that one or more close blood relatives—such as a mother, sister, or daughter—have been diagnosed with breast cancer, especially at a younger age. This can increase your own risk.
Yes. Dense breast tissue (meaning more glandular and connective tissue than fatty tissue) is linked to a higher risk of breast cancer and can make tumors more complicated to detect on mammograms.
Discuss a personalized risk assessment plan with your doctor. BCRF-supported research shows that in premenopausal women, a family history of breast cancer is associated with having dense breasts, highlighting the importance of earlier, enhanced screening.
No. Breast density cannot be detected by look or feel. Only a mammogram—or, in some cases, advanced imaging methods—can accurately determine breast density.
The more information BCRF investigators can compile about people’s family history of breast cancer, the more meaningful their studies will be. Sharing these details helps investigators study inherited risk and understand how genetics influence breast density. And these studies can inform the development of better risk assessment and potentially lead to more targeted screening and prevention strategies.
