Dense Breasts & Breast Cancer Risk
Did you know that almost half of the population of women over 40 have dense breast tissue?
On Thursday, March 9th, the FDA released a press release announcing that as of September 10, 2024, mammogram providers will be required to notify all patients if their breasts are “dense” or “not dense” in the letter they receive after their mammogram. Providers will also be required to explain to all women that dense tissue makes it harder to find breast cancer on a mammogram and increases breast cancer risk. Having this information will help a patient create a comprehensive breast health strategy with her healthcare provider.
In addition, the FDA will evaluate facilities to determine whether to award a certificate that verifies compliance with the new agency requirements. It’s wonderful that the FDA is strengthening its quality requirements. You can read more about this here.
I reached out to Robin Seitzman, Ph.D., MPH, Director of Education and Epidemiology Research at DenseBreast-Info.org to help us understand the meaning of “dense breasts” in more detail. She was very generous with her time and expertise. I am sure you will find her answers below extraordinarily helpful.
What is the difference between a fatty breast and a dense breast?
All breasts are made up of milk glands and ducts, fibrous tissue (that holds the glands and ducts together), and fat. The glands, ducts, and fibrous tissue are together referred to as “fibroglandular tissue”. Each woman has a unique mix of fat and fibroglandular tissue in her breast, and the more fibroglandular tissue compared to fat, the “denser” the breast is.
On a mammogram, breasts are assigned one of four breast density categories from A to D. The two highest categories — “heterogeneously dense” (category C) and “extremely dense” (category D) are considered “dense”. “Fatty” breasts (category A) and “scattered density” (category B) are considered “not dense”.
I have read that if you have dense breasts, you have a higher risk of breast cancer. Is that because it is harder to read the mammogram, or do dense breasts have more incidence of turning into cancer?
Having dense breasts both increases the risk of developing breast cancer and of having that cancer hidden or “masked” on a mammogram and go undetected. These are separate risks, and the greater the breast density, the greater is each of these risks.
Compared to women with fatty breasts (the least dense breasts, or category A) women with heterogeneously dense breasts (category C) have about 2.5-fold greater risk of breast cancer and women with extremely dense breasts (the densest breasts, or category D) have about 4-fold greater risk.
In addition to the increased risk of developing breast cancer, cancers in women with dense breasts can be very difficult to detect on a mammogram. This is because, on a mammogram, both dense tissue and many cancers appear white. Some say it is like trying to see a snowball in a blizzard. It is important for women to know that there are tests that can be performed after a mammogram, like MRI or ultrasound, that can detect more cancers in women with dense breasts.
I understand that having dense breasts are common in women of mammogram age:
- More than 50% of women under the age of 50
- 40% of women in their 50’s
- 25% of women 60 and over
Why does the % decrease with age?
Yes, having dense breasts is normal and common. Breasts tend to become less dense with age, especially after menopause. As hormone levels drop, glandular (dense) tissue shrinks and can be replaced with fatty tissue.
Though breasts become less dense after menopause for some women, others will always have dense breasts. In addition, taking combined estrogen and progesterone hormone supplements (hormone replacement therapy, or HRT) can increase breast density.
Though dense breasts are normal and common, it is important for women to know their own breast density, and what the limitations of mammograms may be for them.
If a woman has dense breasts, what extra screening does she need?
Other screening methods such as MRI, contrast-enhanced mammography (CEM), and ultrasound, will find additional cancers not seen on 2D or 3D mammography alone in women with dense breasts. Women considered to be at high risk of breast cancer (whether or not they have dense breasts) are recommended to have annual MRI screening (or ultrasound if MRI is not possible) in addition to annual mammography.
Having regular, formal risk assessment with a health care provider is important, as women with dense breasts and family history, prior atypical biopsy, or a combination of other risk factors will often qualify as high risk for purposes of annual MRI screening.
While all additional screening tests find more cancers than mammograms alone, with any additional screening test, there is also added risk of being called back for additional testing for findings that turn out not to be cancer (false alarms). Other considerations include the need for contrast injection and claustrophobia for MRI and cost. A shorter “abbreviated” MRI, which is becoming more available, can be performed at a lower cost and may be better tolerated.
Insurance coverage for additional screening tests such as ultrasound or MRI varies by state and insurance carrier. Women can check with their insurance carrier to see if additional tests will be covered and whether co-pays apply. A bill was recently introduced in Congress called the “Find it Early” act which, if passed, would require all insurance carriers to cover additional screening in women at high risk of breast cancer and in women with dense breasts without any co-pays. Women can visit FindItEarlyAct.org to learn how to support the passage of this bill.
If I have dense breasts, should I request a 3-D mammogram vs. a 2-D mammography?
Yes. 3D mammography, or tomosynthesis, has advantages over 2D mammography and is standard at many imaging centers. 3D mammograms slightly improve cancer detection and reduce false alarms (callbacks for additional testing for things that turn out not to be cancer) compared to 2D mammography.
There are other screening tests, such as MRI or ultrasound, that improve cancer detection in women with dense breasts, even after 3D mammograms. Women should discuss with their healthcare providers whether one of these tests is right for them.
I understand 90% of women do not know their breast cancer risk. Early-stage breast cancer is treatable and survivable. Therefore, it seems essential for women to be able to determine their risk of developing breast cancer. Can you guide women on how to evaluate their risk?
As mentioned, annual MRI screening in addition to mammography is recommended for women considered to be at high risk for breast cancer. All women, regardless of breast density, should discuss their risk factors (including breast density, family history of breast cancer, prior chest radiation therapy, personal history of breast cancer, prior atypical breast biopsies or lobular carcinoma in situ, prior benign biopsies, body mass index) with their healthcare providers and determine if they should have additional screening. The IBIS or Tyrer-Cuzick model is the most accurate and can be completed with the assistance of their provider; a lifetime risk of breast cancer 20% or greater is considered “high risk” and should prompt a recommendation for screening MRI for women age 70 or younger in good health.
I asked Robin, what her parting words are to the sisterhood. She reiterated the following:
It is important for both women and their healthcare providers to understand that having dense breasts both increases the risk of developing cancer and of having that cancer hidden on a mammogram. A normal mammogram report in a woman with dense breasts does not mean that cancer is not there; it means that cancer was not seen, which is an important distinction. There are limits to the effectiveness of mammography in women with dense breasts. Women need to be their own advocates and shouldn’t be afraid to initiate discussions with their providers about whether additional screening beyond mammography is right for them.”
Ladies, this information is empowering! Take it and advocate for your own personal breast health. For additional information, please visit www.DenseBreast-info.org, the world’s leading resource for medically sourced, peer-reviewed information on the topic.
Share this info with your sisterhood. It’s the breast thing you can do!
My motto: Suffering in silence is OUT! Reaching out is IN.
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For health advocate and menopause expert Ellen Dolgen, menopause education is a mission. Spurred by her own experience struggling with the symptoms of menopause, Dolgen has devoted the last ten years of her life to helping other women during this often difficult time.
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