A new FDA rule regarding mammography reporting went into effect in September. Among the changes is a new standard for how practitioners talk to patients about breast density after a breast cancer screening.
From now on, your doctor will tell you if your breast tissue is either "dense" or "not dense" after a mammogram or mammography, which provides an x-ray picture of the breast. But what does this mean? We talked to two doctors about how breast density is measured, whether it increases your risk of breast cancer and why it may change over your lifetime.
Regardless of your breast density, Breast Cancer Awareness Month is a great time to schedule a mammogram. The American Cancer Society recommends that people at average risk for breast cancer start getting screened at age 40. You can also regularly check yourself for breast cancer at home at any age.
What is breast density?
Breast density refers to the way your breast tissue looks on a mammogram. Dense tissue is difficult to see through on the mammogram, while less dense tissue is more transparent. Many people have dense breast tissue (about 4 out of 10 women have heterogeneously dense breast tissue), and if your doctor tells you you're among them, it doesn't mean anything is wrong.
There are four categories used to measure breast density. The categories are based on descriptions from the American College of Radiology's Breast Imaging Reporting and Data System (BI-RADS). You may see a category listed as A through D on your breast imaging report.
A: Almost entirely fatty. There will be very little dense breast tissue. B: Scattered areas of density. The breast tissue is still mostly fatty, but there are a few areas of dense tissue.C: Heterogeneously dense. This breast tissue is mostly dense but there are some pockets of fatty tissue.
D: Extremely dense. In this case, most of the tissue is dense and there is very little fatty tissue on the mammogram.
What does dense breast tissue mean?
Breasts have three types of tissue: fibrous, glandular and fatty. Fibrous tissue holds your breast together, while glandular tissue contains the lobes or parts of the breast necessary for breastfeeding or chestfeeding. As for fatty tissue, it provides breast shape and size. Combined, fibrous and glandular tissue are called fibroglandular tissue.
We asked Dr. Michelle Townsend-Day, chief of breast imaging for MedStar Union Memorial and MedStar Good Samaritan Hospitals in Baltimore, Maryland, what this means for interpreting mammograms. She explained that practitioners who assess mammogram results are looking at both "fatty tissue, which is black on mammograms, and fibroglandular tissue, which is white on mammograms."
Fibroglandular tissue appears white on a mammogram because it is more dense than fatty tissue.
How much of your tissue must be white on the mammogram before it's considered dense? Dr. Townsend-Day says, "Dense breast tissue means that the breast is made up of 50% to 100% fibroglandular tissue."
If your breast tissue is dense, it may be easier for a radiologist to miss an abnormality. That being said, there is no need for immediate alarm. Breast tissue can be both dense and completely healthy.
Dense breast tissue causes
It's quite common for patients to be told they have a lot of fibroglandular breast tissue, especially if they're premenopausal. Dr. Anna Cabeca of The Girlfriend Doctor, says there are different reasons why your breast tissue may be dense. She told us the following four factors are the most common:
Heredity: Genetics can influence breast density. Some people have a higher predisposition to dense breast tissue than others simply because of genes.
Age: Younger people can have dense breast tissue because they have more glandular tissue, which is needed for breastfeeding or chestfeeding. As these people age, particularly post-menopause, this glandular tissue is often replaced by fat, which is less dense.
Weight: People with a lower BMI tend to have more dense breast tissue.
Hormones: Higher hormone levels in younger people may also increase breast density. Hormone replacement therapy (HRT) can also increase breast density for people in menopause.
How to find out if you have dense breast tissue
You can't detect your breast density at home. You will need professional imaging to determine how much fatty tissue you have in your breast tissue versus fibroglandular tissue.
In recent years, some organizations have changed their recommendation for when people should begin getting mammogram scans. For instance, the US Preventive Services Task Force, a non-government organization composed of volunteer medical experts, recently lowered their recommendation from age 50 to age 40.
The American Cancer Society (ACS) still says mammograms are optional between ages 40 and 44, but all people of average risk should begin regular screenings at age 45.
If you have a history of breast cancer in your family or other risk factors, your doctor may want you to start screenings sooner. The ACS notes that people at high risk should start getting breast MRIs and mammograms at the age of 30.
Should you get additional screenings if you have dense breast tissue?
Dense breast tissue doesn't automatically demand additional testing, but doctors may suggest it in some cases.
As Dr. Cabeca reminds us, "It is harder to read a mammogram on breasts that have dense tissue because they appear white on the images. That makes the regular tissue harder to discern from potential masses, which also appear in white." Because of this common issue, the doctor says that people "with dense breast tissue may get called back for additional tests more often."
If you get called back for more testing, it's likely to be for another noninvasive screening. Dr. Townsend-Day states, "Additional screening modalities such as breast ultrasound and breast MRI are beneficial in patients with dense breasts to improve cancer detection."
Breast ultrasound: An ultrasound may help a practitioner examine a lump that can be felt but not detected on a mammogram or determine whether the lump is a cyst or solid mass.
Breast MRI: An MRI is sometimes used in combination with mammography because it can find some cancers missed by mammograms. If breast cancer has already been diagnosed, a breast MRI can also provide more information on the size and location of the cancer.
The Affordable Care Act (ACA) mandates health insurance companies cover annual breast cancer screenings for people over 40 with no out-of-pocket costs. If you're high-risk and your doctor recommends screenings before age 40, your insurer is still likely to cover it with a copay.
What to do if you have dense breast tissue
Dr. Townsend-Day told us there is nothing patients can do to alter their breast tissue. Dr. Cabeca agrees, elaborating, "Breast density is a moving target; it is not the same throughout your lifespan. As things in your body change and your hormonal balance shifts, so will the density in your breasts."
If you have dense breast tissue and think you may be a good candidate for more frequent mammograms, discuss your concerns with your doctor. In the meantime, you can still be proactive in staying cancer-free. The American Cancer Society suggests that the following steps could help people lower their risk of breast cancer:
Exercise regularly: Physical activity is linked to a lower risk of breast cancer. Aim for at least 75 minutes of vigorous activity or at least 150 minutes of moderate physical activity each week.
Limit alcohol intake: Even small amounts of alcohol have been linked to an increase in breast cancer risk. Drink no more than an average of one drink per day to avoid heightened risk.
For those at an increased risk for breast cancer, you may also want to consider:
Get genetic testing: Genetic counseling and testing can help you determine if you are predisposed to breast cancer, including carrying the BRCA1 or BRCA2 gene. If you have an increased risk, your doctor may recommend more screenings.
Consider estrogen blockers: Some people with an increased risk of breast cancer may benefit from medications that block estrogen in breast tissue.
Does dense breast tissue increase your breast cancer risk?
Having dense breast tissue does increase your risk of breast cancer. Researchers are still working to more clearly understand this causal relationship, but there is a general consensus among experts. The ACS suggests that dense breast tissue simply has more cells that could turn into abnormal (cancer) cells. The Breast Cancer Research Foundation states that breast cancer tends to develop in glandular tissue, so having more dense glandular tissue than fatty tissue may increase your risk of breast cancer.
Dr. Townsend-Day says that dense breast tissue increases your chances of developing breast cancer by 1.5 times over your lifetime. She also reiterated that dense breast tissue can hide breast cancer better because dense breast mammograms are more challenging to interpret.
People with dense breast tissue should "be a little more vigilant," according to Dr. Cabeca. She says glandular tissue makes people more vulnerable to cancer but adds, "Of course, you also have estrogen-based cancer, which is a totally different type of breast cancer. I wouldn't say that less density in the breast tissue means you can't get cancer, but as a rule, the density makes your breast more glandular and harder to read on a mammogram."
The bottom line
Dense breast tissue is more difficult to interpret on a mammogram film, which makes detecting breast cancer harder. Most pre-menopausal people find themselves with dense tissue. This makes regular screening important.
If you're at average risk of breast cancer, consider getting your first mammogram at age 40 to give your doctor a baseline. People at any risk level should practice monthly self-breast exams. Let your doctor know if you feel any changes to your breast tissue, including lumps.