Many women underestimate breast density as a risk factor for breast cancer, study finds


Dense breast tissue has been linked to an up to four times higher risk of breast cancer. However, a new study suggests that few women consider breast density to be a significant risk factor.

The study, published in JAMA Network Open, surveyed 1,858 women aged 40 to 76 from 2019 to 2020 who said they had recently had a mammogram, had no history of breast cancer and had heard of the density breast.

The women were asked to compare the risk of breast density to five other breast cancer risk factors: having a first-degree relative with breast cancer, being overweight or obese, drinking more than one alcoholic beverage a day, never having children and having had breast cancer before. biopsy.

“Compared to other known and perhaps more well-known breast cancer risks, women did not perceive breast density as a significant risk,” said Laura Beidler, study author and researcher at the Dartmouth Institute for Health Policy and Clinical Practice. .

For example, the authors report that dense breast tissue is associated with a 1.2- to four-fold increased risk of breast cancer compared to a two-fold increased risk associated with having a first-degree relative with breast cancer. breast cancer – but 93% of women said breast density was a lower risk.

Dense breast tissue refers to breasts that are made up of more glandular and fibrous tissue than fatty tissue. This is a normal and common finding in about half of women having a mammogram.

The researchers also surveyed 61 participants who said they had been told about their breast density and asked them what they thought contributed to breast cancer and how they could reduce their risk. While most women correctly noted that breast density could mask tumors on mammograms, few women believed that breast density could be a risk factor for breast cancer.

About a third of women thought there was nothing they could do to reduce their risk of breast cancer, although there are several ways to reduce the risk, including maintaining a healthy, active lifestyle and reducing Alcohol consumption.

Breast density changes over a woman’s lifetime and is generally higher in women who are younger, who have lower body weight, who are pregnant or breastfeeding, or who are on hormone replacement therapy.

The level of breast cancer risk increases with the degree of breast density; however, experts are unsure why this is true.

“One hypothesis is that women who have denser breast tissue also have higher levels of estrogen, circulating estrogen, which contributes to both breast density and the risk of developing breast cancer,” said breast specialist Dr. Harold Burstein. oncologist at the Dana-Farber Cancer Institute who was not involved in the study. “Another hypothesis is that there is something in the tissue itself, making it more dense, that somehow predisposes to the development of breast cancer. We don’t really know which explains the ‘observation.

Thirty-eight states currently require women to receive written notification of their breast density and its potential risk of breast cancer after mammography; however, studies have shown that many women find this information confusing.

“Even though women are usually notified in writing when they receive a report after a mammogram that says, ‘You have increased breast density’, it’s kind of just hidden at the bottom of the report. I’m not sure anyone explains to them, certainly in person or verbally, what that means,” said Dr. Ruth Oratz, a breast oncologist at NYU Langone’s Perlmutter Cancer Center who was not involved in the study.

“I think what we’ve learned from this study is that we need to better educate not only the general public of women, but also the general public of health care providers who do primary care, who order these screenings .mammograms,” she added.

Current screening guidelines recommend women at average risk for breast cancer undergo breast cancer screening every one to two years between the ages of 50 and 74 with the option to start at age 40.

Since women with dense breast tissue are considered to have higher than average cancer risks, the study authors suggest that women with high breast density may benefit from additional screening such as MRI breast cancer or breast ultrasound, which can detect cancers missed during mammograms. Currently, coverage for additional screening after the initial mammogram varies by state and insurance policy.

The authors warn that “additional screening may not only lead to increased cancer detection rates, but may also lead to more false positive results and recall appointments.” They say clinicians should use risk assessment tools when discussing the trade-offs associated with additional screening.

“Usually it’s a discussion between the patient, the clinical team and the radiologist. And that will be affected by the history, by whether there’s anything else to worry about on the mammogram, by the patient’s family history. So those are the kinds of things that we frequently discuss with patients who find themselves in such situations,” Burstein said.

Breast cancer screening recommendations differ from one medical organization to another, and experts say women at higher risk due to breast density should talk to their doctor about how and how often to get screened. most appropriate.

“I think it’s really, really important for everyone to understand – and it’s the doctors, the nurses, the women themselves – that screening is not a one-size-fits-all recommendation. We can’t just make a general recommendation for the whole population, because individual women have different levels of risk for developing breast cancer,” Oratz said.

For nearly a third of women with dense breast tissue who said there was nothing they could do to prevent breast cancer, experts say there are some steps you can take to lower your risk.

“Maintaining an active, healthy lifestyle and reducing alcohol consumption takes into account several modifiable factors. Breastfeeding can lower the risk. On the other hand, the use of hormone replacement therapy increases the risk of breast cancer,” said Dr. Puneet Singh, a breast surgical oncologist at MD Anderson Cancer Center who was not involved in the study.

The researchers add that there are approved drugs, such as tamoxifen, which can be given to people at significantly increased risk and which can reduce the risk of breast cancer by about half.

Finally, breast cancer doctors say that in addition to proper screening, knowing your risk factors and advocating for yourself can be powerful tools in preventing and detecting breast cancer.

“At any age, if a woman feels uncomfortable about something going on in her chest, feels discomfort, notices a change in her chest, bring it to the attention of your doctor and make sure it’s valued and don’t let somebody just push you away,” Oratz said.

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