Breast Density and Mammograms: Why It Matters
If you’ve had a mammogram, you may have heard your doctor mention breast density in your results. It’s a term that often raises questions. Breast density isn’t something you can feel or see, it can only be identified through imaging, and it plays a significant part in both breast cancer detection and risk.
What Is Breast Density?
Breast density refers to the proportion of fibrous and glandular tissue compared to fatty tissue in the breast. On a mammogram, dense tissue appears white, while fatty tissue appears darker or grey.
Breast density is usually categorised into four levels:
- Almost entirely fatty
- Scattered areas of fibroglandular density
- Heterogeneously dense (may obscure small masses)
- Extremely dense (lowers the sensitivity of mammograms)
Women in the last two categories, heterogeneously dense or extremely dense, are considered to have dense breasts.
Why & How Breast Density Affects Mammograms
Dense breast tissue makes it more challenging to spot abnormalities on a mammogram. Because both dense tissue and potential tumours appear white on the image, it can be difficult to distinguish between the two during imaging.
This doesn’t mean mammograms are ineffective, but it does mean that detecting cancer in dense breasts can be more challenging for doctors. Research shows that mammograms may miss a significant percentage of cancers in women with dense breast tissue, and that a supplementary breast MRI would produce optimal detection results. Breast density is therefore an important factor to consider in screening and diagnosis.
Does Breast Density Affect Cancer Risk?
Yes, breast density is linked to an increased risk of developing breast cancer. Women with extremely dense breasts may have a risk that is four to six times higher than women with mostly fatty tissue.
While the exact reasons for this increased risk are still being studied, the presence of more glandular tissue may provide additional areas where cancer could develop.
What Are the Next Steps If You Have Dense Breasts?
If your mammogram shows dense breast tissue, your doctor may recommend additional imaging. This might include:
- Breast ultrasound, which can help detect abnormalities that mammograms might miss.
- Breast MRI, often used for women at higher risk or with dense breasts to provide more detailed images.
The approach depends on your overall risk profile, family history, and your doctor’s guidance.
Can Breast Density Change?
Yes. Breast density can change over time due to age, hormonal changes, menopause, or certain medications. It is common for density to decrease after menopause, but some women continue to have dense breasts as they get older.
Why Knowing Your Breast Density Matters
Understanding your breast density helps ensure that your screening plan is as effective as possible. It allows your healthcare team to choose the most suitable imaging options and supports early detection, when treatment is most successful.
If you have been told you have dense breasts, speak to your doctor about whether you might benefit from supplemental imaging or more frequent screening.
For high-quality mammography and advanced breast imaging, consider booking your screening at MBR Our team combines expertise with the latest technology to support accurate and early diagnosis.