If you have dense breasts, you may worry that it could affect your chances of developing breast cancer—or your outcome of that disease.
Dense breasts are common. In fact, nearly half of all women who are 40 and older who get mammograms are found to have dense breast tissue, according to the National Cancer Institute.
In this Q&A, Stephanie Bernik, MD, FACS, Chief of Breast Service at Mount Sinai West and Associate Professor of Surgery at the Icahn School of Medicine at Mount Sinai, explains how having dense breasts can affect a mammogram and the chances of developing breast cancer.
What are dense breasts?
If your doctor tells you that you have dense breasts, it means that you have a lot of glandular tissue and less fat throughout the breast. You can’t tell if you have dense breasts just by looking at them; you need an imaging test. Mammograms are our number one screening tool.
How common are dense breasts?
Most women have dense breast tissue when they’re younger. As you get older, your breasts usually become less dense. That’s not true for everyone. There are older patients, people in their 70s or 80s, who still have dense breast tissue. But because young women very often have dense breasts, we don’t start screening with mammograms until you’re 40, unless you have a family history of breast cancer. Mammograms before that age are not really useful, because of the breast density.
Do dense breasts affect mammograms?
When we look at a mammogram, dense tissue appears white; it can obscure cancer because cancer also shows up as white on mammograms. So dense breasts can make it harder to read a mammogram. If we’re unsure at all, we follow up with another form of imaging to take a closer look—usually a sonogram or magnetic resonance imaging (MRI).
Does nursing affect breast density?
When people are breastfeeding, their breast tissues usually becomes denser because the glandular tissue is simulated. That’s why mammograms are less useful when you’re nursing. After you finish breastfeeding, the tissue isn’t being stimulated, so your breasts go back to how they were before.
Does breast density affect your chances of developing breast cancer? Why?
Women with dense dense breast tissue are about four times as likely to develop breast cancer than other women. The reason for this is that dense breasts have more glandular tissue and that’s where the cancer grows, in glandular tissue. So women with more glandular tissue have more space for cancer to develop.
What are the signs of breast cancer in dense breasts?
The signs of breast cancer in dense breasts are the same as with any other person. You might feel a mass, or it shows up on a mammogram. Imaging tests (including mammograms) can also show calcifications, which are calcium deposits in the breast and can sometimes be a sign of cancer. But just because you have a possible sign of breast cancer doesn’t mean you actually have cancer. These findings may require more imaging or a biopsy. Most breast masses we find are benign; there are many different kinds of benign breast masses. Calcifications are generally benign, too.
Does having dense breasts affect the diagnosis and treatment of breast cancer?
Dense breasts can sometimes obscure cancer. So we might not find the cancer until it is a little bigger. But that usually doesn’t affect the outcome.
Is a breast self-exam less effective when you have dense breasts?
Not necessarily. The key to an effective breast self-exam is knowing your breast so you can tell if there’s a change. Most women start to do self-exams in their 20s. If you don’t know your breasts, you might do a self-exam and you think you feel something, but it turns out to be just a benign mass or normal breast tissue, which is not cancerous. That’s why there’s some controversy over self-exams. If you know your breasts and feel something new, that’s helpful. But if you don’t do the exams often enough (for example, monthly) to learn your breasts, it may be less helpful. For that reason, if you’re not comfortable with doing a breast exam, we don’t tell you that you have to do it.
What can someone with dense breasts do to lower their chances of getting breast cancer?
You can do the same thing anyone can do to decrease their cancer risk. Exercise, eat a healthy diet with lots of fruits and vegetables, maintain a healthy weight, limit alcohol consumption, and don’t smoke. This helps lower your risk of breast cancer—and other cancers.