Many Women Don't Think Breast Density Is Important Risk Factor
Most women don’t realize that breast density ups breast cancer risk more than family history or being overweight or obese, according to a survey of more than 2,000 women. Many women also didn’t understand they could take steps to keep their risk of breast cancer as low as it could be.
The research was published online on Jan. 23, 2023, by the journal JAMA Network Open. Read “Perceptions of Breast Cancer Risks Among Women Receiving Mammograph Screening.”
Breast cancer risk factors
Every woman has some risk of breast cancer. The average risk of breast cancer in women is about 13%. Still, there are a number of factors that can make that risk higher, including:
Your breasts are made up of fibrous tissue, glandular tissue (the tissue that produces milk), and fatty tissue. If you have dense breasts, it means you have more fibrous and glandular tissue and less fatty tissue than women who don’t have dense breasts. Having dense breasts is normal; it is not a medical condition itself, and it does not cause symptoms. You can’t tell whether or not you have dense tissue by feeling the breasts. Dense breast tissue can only be seen on a mammogram. Fatty tissue appears dark on a mammogram, and dense tissue appears white. About half the women who have mammograms have dense breasts.
Dense breasts are associated with a risk of breast cancer that is up to four times higher than the average.
Women with a first-degree relative (parent, sibling, child) diagnosed with breast cancer have about twice the average risk of breast cancer.
The connection between weight and breast cancer is complicated. We know that having more fat tissue raises estrogen levels, and high estrogen levels are linked to a higher risk of hormone receptor-positive breast cancer. Some research suggests that women who gain weight as adults have a higher-than-average risk of breast cancer, but women who have been overweight since childhood don’t seem to have a higher risk.
Women who have their first child after age 30 or who haven’t had a full-term pregnancy have a higher risk of breast cancer than women who give birth before age 30. When breast cells are made in adolescence, they are immature and very active until a woman’s first full-term pregnancy. The immature breast cells respond to the hormone estrogen as well as hormone-disrupting chemicals in products. Your first full-term pregnancy makes the breast cells fully mature and grow in a more regular way. This is the main reason why pregnancy helps protect against breast cancer.
Women who are older when they have their first baby or who never have a full-term pregnancy have a higher breast cancer risk because they are exposed to more estrogen in their lifetimes. Their breast cells also take longer to fully mature. Still, it’s unclear exactly how much never having a child increases breast cancer risk.
Research consistently shows that drinking alcoholic beverages — beer, wine, and liquor — increases a woman’s risk of hormone-receptor-positive breast cancer. Alcohol can increase levels of estrogen and other hormones associated with hormone receptor-positive breast cancer. Alcohol also may increase breast cancer risk by damaging DNA in cells.
Women who have three alcoholic drinks a week have about a 23% higher risk of breast cancer than women who don’t drink at all. Experts estimate that the risk of breast cancer goes up another 10% for each additional drink women regularly have each day.
If you’ve had a breast biopsy, it means your doctor saw something on a mammogram or other screening test or felt a lump and wants to figure out if it’s cancer or not. Although breast biopsies themselves do not cause cancer, the breast changes that lead to a biopsy can increase breast cancer risk, especially if a biopsy shows excessive growth of abnormal-looking cells.
About the study
The researchers surveyed 2,306 women who were a representative sample of women in the United States.
The women were ages 40 to 76 and:
had had a mammogram in the past two years
had never been diagnosed with breast cancer
had heard of breast density
Of the women in the study:
43% were white
27% were Black
14% were Hispanic
9% were Asian
7% were Pacific Islander, Native American, mixed race, or other race not listed
84% were classified as having high literacy levels
16% were classified as having low literacy levels
76% lived in a state with a law that requires women to be notified about breast density after a mammogram
The survey focused on the women’s perceptions of breast cancer risk factors. The researchers asked the women to compare the increase in breast cancer risk linked to having dense breasts with five other risk factors:
having a first-degree relative with breast cancer
being overweight or obese
having more than one alcoholic drink per day
never giving birth
having had a breast biopsy
For each risk factor, the women were asked, “Which do you think puts someone at greater risk for developing breast cancer?”
When comparing the other risk factors with having dense breasts:
93% of the women thought a family history of breast cancer increased risk more than having dense breasts
65% of the women thought being overweight or obese increased risk more than having dense breasts
52% of the women thought having dense breasts increased risk more than not giving birth
53% of the women thought having dense breasts increased risk more than having more than one alcoholic drink a day
48% of the women thought having dense breasts increase risk more than having had a breast biopsy
After the women completed the survey, the researchers did telephone interviews with 61 women who said they knew their breast density. The researchers asked the women to identify what they thought contributed to their risk of breast cancer, as well as how they thought they could reduce their risk.
Of the 61 women:
27% were white
25% were Hispanic
25% were Asian, Pacific Islander, Native American, mixed race, or other race not listed
23% were Black
Few of the women interviewed thought that breast density contributed to their risk of developing breast cancer. On the other hand, most women knew that breast density could make a mammogram harder to read.
Most of the women thought that a family history of cancer or genetic factors contributed to their personal risk of breast cancer, and many of the women thought family history meant their risk was much, much higher than average. Women with no family history of breast cancer thought they had a minimal risk of breast cancer.
The researchers ranked the risk factors the women identified by how frequently each factor was mentioned:
family history and genetics
diet
smoking
lifestyle, including stress, medicines, and exercise
environmental factors
breast density
obesity
alcohol
pregnancy history
As far as steps that could reduce breast cancer risk, many of the women thought that screening methods, such as mammograms and breast self-exams, could reduce risk, which isn’t correct. Screening tests are important because they can detect breast cancer early, when it may be more treatable. But screening can’t reduce the risk of breast cancer.
The researchers ranked the steps that could reduce risk according to the women by how frequently each step was mentioned:
timely mammograms
eating a healthy diet
doing breast self-exams
exercising regularly and maintaining a healthy weight
avoiding or quitting smoking
avoiding specific environmental exposures, such as chemicals
avoiding or limiting alcohol
avoiding physical injury to the breasts
Nearly 30% of the women said they weren’t sure if it was possible to reduce their risk or that they didn’t know what steps they could take to reduce their risk.
“This… study demonstrated that women perceived family history as the strongest risk factor for breast cancer, with mixed perceptions about other lifestyle or clinical risk factors in relation to breast cancer risk,” the researchers wrote. “Among interview respondents who knew their breast density, few women noted breast density as a breast cancer risk factor. Few women understood options for mitigating their personal breast cancer risk. Despite breast density being associated with a 1.2 to 4 times higher risk of breast cancer, few women perceived breast density to be a strong personal risk factor.
“Women perceived family history as highly deterministic of future breast cancer,” they continued. “Women without a family history believed they were safe or had limited risk based on this factor alone.”
What this means for you
The results of this study are concerning. They seem to indicate that not many women understand the breast density notifications they receive. They also strongly suggest that many women who don’t have a family history of breast cancer think they have very low risk, even if they have dense breasts.
In the United States, 38 states and Washington, D.C., require breast imaging centers to give women some level of information about breast density after their mammogram. U.S. federal law requires that all women receive a letter notifying them about the results of their mammogram.
In most states, this form letter also tells you if you have dense breasts, and in some states, it lets you know your specific density category. The letter’s content varies widely by state and may not necessarily include specific details about your situation. Most of the letters advise you to discuss your results with your doctor. Your breast density is also included in the final mammography report to your healthcare provider, prepared by the radiologist who read the images.
If you live outside the United States, you may or may not be notified about your breast density, depending on your country’s regulations. DenseBreast-info.org is a good resource for finding out what the laws are where you live.
Regardless of whether you get a letter about breast density, it makes sense to ask your doctor if you have dense breasts and how it affects your personal breast cancer risk. If you’re among the 10% of women with extremely dense breasts, it makes sense to ask your doctor about having a second test, such as an ultrasound or a breast MRI, in addition to a mammogram, as part of your routine screening. Additional screening for dense breasts isn’t yet considered the standard of care and isn’t done routinely, so you may need to bring this up with your doctor.
It’s also important to know that there are steps every woman can take to keep her risk of breast cancer as low as it can be. You can’t change some risk factors, such as your age or your breast density, but you can make sure your lifestyle is as healthy as possible by:
eating a diet low in added sugar and processed foods and rich in unprocessed, nutrient-dense foods
exercising regularly at the highest intensity level you’re comfortable with
avoiding or limiting alcohol
not smoking
Learn more about breast cancer risk factors and other steps you can take to keep your breast cancer risk as low as it can be.
Editor’s Note: In March 2023, the U.S. Food and Drug Administration (FDA) updated mammography regulations to make breast density reporting a national requirement. Each mammography facility must give women information about the density of their breasts, using specific language explaining how breast density can affect the accuracy of a mammogram and recommending that women with dense breasts talk to their doctors about breast density and how it affects their personal risk of breast cancer.
— Last updated on May 25, 2023 at 3:18 PM