What is breast density?

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Kathleen V. Greatrex, MD
Diagnostic Radiology
Breast density refers to the type of tissue inside your breasts. It is not about how your breasts feel or look in the mirror.

Some breast tissue is fatty. Other tissue in the breast is dense. It is made of thick, fibrous tissue and milk glands, or glandular tissue. Breasts are considered dense if you have less fatty tissue and more of the thick, fibrous and glandular types.

Four in 10 women have dense breasts. Younger women's breasts tend to be denser than those of older women who have gone through menopause. Breast density can be passed down through families, or inherited. That means if your mother has dense breasts, you may as well.

On a mammogram, fatty tissue appears dark. Dense tissue shows up white, just like cancerous tumors or other suspicious masses.

Looking for a tumor within dense breast tissue can be like trying to find a snowball in a blizzard. We don't want to miss anything, so we may recommend additional tests.
 
Trinity Health is a Catholic health care organization that acts in accordance with the Catholic tradition and does not condone or support all practices covered in this site. In case of emergency call 911. This site is educational and not a substitute for professional medical advice, always seek the advice of a qualified healthcare provider.
Jennifer Rollenhagen, MD
Diagnostic Radiology
Breast density may be a marker for breast cancer risk and is a factor in screenings and diagnosis. In this video, radiologist Jennifer Rollenhagen, MD, of Mercy Health, explains how breast density can impede a breast cancer diagnosis.

Trinity Health is a Catholic health care organization that acts in accordance with the Catholic tradition and does not condone or support all practices covered in this site. In case of emergency call 911. This site is educational and not a substitute for professional medical advice, always seek the advice of a qualified healthcare provider.
Michael Paciorek, MD
Diagnostic Radiology
Breast density describes the composition of tissues in the breast. In this video, Michael Paciorek, MD, of Mercy Health, outlines the four categories of breast density and explains the impact of breast density on cancer screening and diagnosis.

Trinity Health is a Catholic health care organization that acts in accordance with the Catholic tradition and does not condone or support all practices covered in this site. In case of emergency call 911. This site is educational and not a substitute for professional medical advice, always seek the advice of a qualified healthcare provider.
Jamie L. Caughran, MD
Surgery
Breast density refers to how your breast tissue appears on your mammogram. In this video, Jamie Caughran, MD, FACS, of Mercy Health, explains the impact your breast density has on your annual screening and overall breast health.

Trinity Health is a Catholic health care organization that acts in accordance with the Catholic tradition and does not condone or support all practices covered in this site. In case of emergency call 911. This site is educational and not a substitute for professional medical advice, always seek the advice of a qualified healthcare provider.
HealthyWomen
Administration
Breast density refers to how well a mammogram can "see" any potential cancers or precancerous conditions within your breasts. Your breasts are made up of fat and fibrous tissue. X-rays penetrate fat tissue fairly well, but don't penetrate fibrous tissue that well. This fibrous tissue, which occurs bilaterally in both breasts, is called "radiodense." It appears on the mammogram as a white area. This makes it very difficult to identify any tumors, which also appear as white. 

Breast density refers to the appearance of the breast tissue on imaging, usually mammogram. All breasts are composed of glandular breast tissue and fat - the more glandular tissue, the more dense the breast. Dense breast tissue appears more "white" on mammogram, which makes it harder to detect cancer, also usually "white" on mammogram. Younger women naturally have dense breast tissue, but some women still have dense breast tissue even as they get older. Hormone therapy will maintain the dense breast appearance on mammogram.

Women with dense breast tissue on imaging are at higher risk for the future development of breast cancer, and as mammograms may miss more cancers in women with dense breast tissue, additional imaging such as ultrasound or MRI may be helpful.

Breast density describes the relative amount of different tissues present in the breast. A dense breast has less fat than glandular and connective tissue. Mammogram films of breasts with higher density are harder to read and interpret than those of less dense breasts.

This answer is based on source information from the National Cancer Institute.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.