What are dense breasts and why do you need to know?

After a mammogram, you may get a letter in the mail that begins something like this: “Your mammogram indicates that you have dense breast tissue.” When I got that letter, I wasn’t sure what it meant for me or what I should do about it. The letter went on a pile of other “non-urgent” mail to think about later.

Later changed to now. That’s because the US Food and Drug Administration has issued a New Rule on Breast Density Information, is part of an update to the mammography regulations. Published March 10, the rule makes these letters a nationwide requirement and standardizes the information contained in them. Previously, 38 states notified people with dense breasts or provided information about breast density after mammograms. The new rule, which will go into effect on September 10, 2024, means that everyone who gets a mammogram will be informed whether their breasts are dense or not.

Why do people need to know this? If you just want to take home the message, here it is: Having dense breasts increases your risk of being diagnosed with breast cancer. But breast density is justified One factor to be considered among others When ascertaining the overall risk of an individual. Having dense breasts doesn’t mean you’ll get breast cancer, and not having dense breasts doesn’t mean you’re in the clear.

Ideally, receiving information about breast density will lead to a detailed discussion with the doctor about breast cancer risk. This column cannot replace that. But if you want to learn more about dense breasts and why focusing on them is a blunt instrument, read on.

What are dense breasts?

Breasts are made up of different types of tissue: glandular tissue, which produces milk and directs it to the nipple, as well as connective (fibrous) tissue and fatty tissue. Dense breasts contain more glandular and connective tissue than fatty tissue.

Having dense breasts “is not unusual,” says Joan Elmore, MD, an internist and epidemiologist at UCLA. Dense breasts are also common: all around 46 percent of women ages 40 to 79 in the United States haveResearchers reported in Journal of the National Cancer Institute In 2019.

A radiologist assesses the density of breast tissue from a mammogram. The two non-dense classifications are “almost entirely fatty” and “scattered areas of fibroglandular density,” meaning predominantly fatty tissue with some areas of dense tissue. About 8 and 46 percent of American women ages 40 to 79, respectively, have these two classifications.

The two dense categories are “disproportionately dense” and “extremely dense,” with an estimated 40 percent and 6 percent of American women 40 to 79 in those categories, respectively. The two dense categories are usually grouped together and are referred to as “dense breasts”. Under the new FDA rule, the notification letters will be worded like this: whether the person’s breast tissue is “dense” or “not dense.”

One more thing: breast density can change. For example, older women tend to have less dense breasts than younger women. and sometimes a person will be changed from “dense” to “not dense” or vice versa, based on radiologist reading the mammogram and deciding between the categories of “scattered areas of density” and “heterogeneous dense”.

OK, so why do I need to know that my breasts are dense?

Dense breasts create two problems. First, on a mammogram, the glands and connective tissue appear as white—which is also what tumors or other abnormal breast tissue look like. This dense tissue can hide what a radiologist is looking for.

One measure of how well a mammogram works is sensitivity, the proportion of tumors detected by the mammogram out of all tumors diagnosed (whether or not detected by the mammogram). An analysis of mammograms from a Dutch screening program found that for those with almost all fatty tissue, the sensitivity was 86 percent, and for scattered areas of density, it was 78 percent. continued decline in sensitivity with greater density: 70 percent for asymmetrically dense breasts and 61 percent for very dense breasts, the researchers report. Breast Cancer Research and Treatment In 2017.

Second, the dense tissue itself contributes to cancer risk. This may be related to the greater amount of glandular tissue in denser breasts. “Breast cancer almost always develops in glandular tissue,” says Priscilla Schlanetz, M.D., a breast radiologist at Boston Medical Center.

By how much do dense breasts increase the risk of being diagnosed with breast cancer?

politely. Dense breasts “elevate you slightly above the average person,” says Slanetz. An average person is someone who does not have any known risk factors for developing breast cancer.

The researchers compared the risk of developing breast cancer in people with dense breasts with those with scattered areas of density, the most common non-dense category. are premenopausal women with asymmetrically dense breasts 1.5 to 1.8 times higher risk of developing breast cancer, on the basis of race and ethnicity. People with extremely dense breasts have a 1.8 to 2.4 times higher risk. For postmenopausal women, the risk was 1.3 to 1.6 times higher for asymmetrically dense breasts and 1.5 to 2 times higher for moderately dense breasts, the researchers report. Cancer Epidemiology, Biomarkers and Prevention In 2020.

Here’s another way to try to explain risk from a hypothetical case study. 47-year-old woman with disproportionately dense breasts and no family history of breast cancer. In case studies, out of 1,000 women who have disproportionately dense breasts, an estimated 20 will develop breast cancer in the next 10 years. This compares with 13 out of 1,000, like the case study woman, but with the most common non-intensified category.

It is also important to know what is the density of the breast. not associated with a higher risk of dying from breast cancer, researchers reported in Journal of the National Cancer Institute in 2012. An analysis of more than 9,000 women with breast cancer shows that what contributes to the development of cancer affects the risk of dying from breast cancer. A separate group of researchers also reported in 2018 No link between breast density and breast cancer deaths,

What other factors should I be aware of regarding breast cancer risk?

Dense breasts are just one part of the risk picture. Slanetz says the two most important risk factors for developing breast cancer are being female and increasing age.

About 1 in 8 or 13 percent of cisgender women in the United States will be diagnosed with breast cancer in their lifetime. an estimated 297,790 new cases of breast cancer in women Expected to happen in 2023. Male account for less than 1 in 100 cases ,Sn: 10/3/19, and risk increases as do birthdays: on average, while 1 in 65 women starts by age 40 According to the National Cancer Institute, 1 in 24 women starting at age 70 will develop breast cancer in the next 10 years.

There are also racial disparities in breast cancer risk. Despite having a slightly lower incidence of breast cancer than white women, black women have a 40 percent higher risk of deathIn the United States, 28 per 100,000 black women die from breast cancer compared to 20 per 100,000 white women. black women are breast cancer detected at a young age, is a more aggressive disease and is diagnosed at a later stage of cancer, all of which contribute to a poor prognosis. disparities in access to cancer treatment And surgical treatments contribute to the disparity.

Breast cancer statistics are lower for transgender men and women. Researchers have found that transgender men have lower rates of breast cancer compared to cisgender women, which appears to be related to surgical removal of the breasts and use of testosterone. Transgender women have a lower risk of breast cancer than cisgender women due to less exposure to the hormone estrogen in their lives, although estrogen therapy may increase the risk.

Among the factors that greatly increase the risk of developing breast cancer are BRCA 1 And BRCA2 genetic mutation. About 7 in 10 carriers of one of the mutations will have breast cancer by age 80. Women who received radiation therapy to the chest as children are also at higher risk. These two groups have specific breast cancer screening recommendations.

Online breast cancer risk calculators can help doctors estimate an individual’s risk. After adding up their risk factors, people are considered high risk if their lifetime chance of developing breast cancer is 20 percent or more. The American College of Radiology recommends getting a mammogram. Start at age 30 for those In high risk, supplement with breast magnetic resonance imaging. The ACR also recommends that black women be assessed for breast cancer risk after age 30.

Doctors say people with dense breasts — as well as those without, and those at average or slightly above average risk — should still get screening mammograms. They have some variation among medical organizations. screening recommendations At what age to start and whether to have annual or every other year mammograms.

What should I do if my breasts are dense?

There are no specific recommendations for denser breasts to guide people or their doctors. People should be aware of their breast density, says Ilana Richman, M.D., a general internist at Yale School of Medicine. “But it’s an open question what to do with that information,” she says, because of the lack of guidelines.

Notifications from some states have suggested that people with dense breasts may benefit from supplemental screening with a different imaging technique, such as MRI or ultrasound. With the new FDA rule, the notifications will say that in some people with dense tissue, adding other imaging tests may help detect cancer early. However, exposure alone is not enough to push someone into the high-risk category, and Carla Kerlikowske, a primary care physician and clinical epidemiologist at the University of California, San Francisco, says supplemental screening is needed. “There are many people who have dense breasts who are actually at a lower risk of breast cancer,” she says.

Ideally, a thorough breast notification will lead to a discussion with a doctor about the various risks for breast cancer, in order to understand a person’s overall risk. But the limited time allotted for primary care visits in the United States is a barrier. “We don’t have a system that can allow enough time to have that nuanced discussion,” says Christina Chapman, MD, a radiation oncologist and health equity researcher at Baylor College of Medicine in Houston.

Also, this conversation should happen with those who do not have normal breasts, who may still be at high risk. “In some ways the focus on breast density distracts from the idea that risk is multidimensional,” Richman says.

Planetz says that many women who develop breast cancer have no obvious risk factors, which is why screening mammograms are important. “we screen [everyone] Because we have to.