Author’s note: Although men can also develop breast cancer, for the purposes of this blog, we focus on women, as they are the majority of potential breast screening patients and the most likely readers of this post.
Thank God we have two breasts!
Why do I say that? Yikes, can you imagine, as a patient, undergoing a multi-breast mammography, or, as the radiologist, having to read more images for every screening patient? And what if there’s an odd number of breasts and they do not all look similar? How can we tell what is normal for that particular woman?
Joking aside, we are glad for paired breasts because comparing the two gives us breast radiologists (your breast imaging doctors) a better idea of what is probably “within normal limits” for each woman – in breast size, breast density (defined below), breast tissue distribution, etc. Most women are similar enough between her two breasts to give us some idea of what is her usual state of being. From there, we carefully assess everything else we see, and when there are comparison older films, even better! So make sure to get your older exams whenever switching facilities. It will always help, never hurt, decreasing some of the avoidable “false positives” – a topic that is outside of the scope of this post.
As you all probably already know, the mammogram is a safe, low-dose x-ray of the breasts. To our eyes, all body tissues will show up somewhere along the gray/black (lucency) to whiteness (density) scale, depending on how easily x-rays penetrate. The whiteness on a mammogram is normal – not-to-be-feared – tissue and referred to as fibroglandular tissue. So breast density level is referring to how we’re rating the amount of whiteness relative to overall breast size on mammography. Our radiology descriptions range from predominantly fatty (not much of any fibroglandular tissue) to extremely dense (most or almost all of the mammo appears white). The gist is that “dense breasts” is the term used when the radiologist rates the mammogram as having more fibroglandular tissue than fat.
Breast density is a specific radiology term and is not the same as how the breasts feel on clinical or self-exam. Many women who are told they have lumpy, fibrous, cystic, fibrocystic, thickening and dense breasts on physical exam may and often do have dense breasts on mammography. But they may not and may be understandably confused if their mammogram shows non-dense breasts. This distinction is important. Mammographic breast density is what we’re talking about, and conveying that is the point of the breast density notification (BDN) legislation that has impacted, so far, 28 states.
Breast density level is, in part, related to a woman’s age, pre- or post-menopausal status, body habitus, ethnicity, history bearing and nursing children and other details – but these do not reliably predict breast density level. The diversity across our U.S. population is wonderful, and we’re used to it. No two people are exactly the same. The mammographic breast density is for us to determine with mammography and include in our clinical report to your referring doctors.
Commonly quoted is that up to 50 percent of U.S. women have dense breasts. Younger women will generally have dense breasts because that is the normal breast tissue that can produce milk, if called upon to do it! Postmenopausal women tend to have less dense breasts, but still about 30 percent of women in their 70s may have dense breast tissue. For everyone, the mammography determines her breast density level.
So why do we care? Breast density can limit how well an average cancer might be visible on dense breast pattern on mammography, especially if it is small and without suspicious calcifications. Higher breast density is also thought to have an association with higher cancer risk. There are theories to this association, but, hold on, this does not mean causal – meaning it’s not that dense tissue causes cancer. Stay calm, take this all in stride and do not fear the dense tissue!
Cancers do not arise in all women with dense tissue. AND cancers do not arise only in women with dense tissue. So don’t be assuming the worst if you know or come to know that you have dense breast tissue, because this is no guarantee that you will get cancer. Remember, 7 out of 8 American women will not develop breast cancer in their lifetimes.
If you don’t have dense breasts, don’t be falsely reassured. Cancers arise in all breast density levels, and more than 75 percent of new cancers are diagnosed in women with no additional risk factors other than being female and aging, and those cancers can be variable in aggressiveness across all ages. So lower density should not be reason to relax mammography guidelines. We still recommend screening all women, because breast cancer is so common and the potential benefit of early detection is available to everyone.
So why are we talking about breast density so much lately and what is the discussion about breast density notification? In 2009, the first state-wide breast density notification law was enacted in Connecticut, driven by the passionate work of Nancy Cappello, PhD, patient-turned-effective advocate. Although the breast density rating is routinely included in the mammo clinical report to referring doctors, the difference is whether women get this information. Dr. Cappello’s work was to require proactively informing patients directly if they have dense breast tissue on mammography, so that they can learn more about dense tissue and consider supplemental screening to add to mammography. The point being that there may be a cancer not visible on mammography and that, if present, could be found by adding another test (supplemental screening, not to replace mammography) like ultrasound. Women deserve the information to know about this possibility.
From then until now, 28 states have passed laws requiring some level of breast density notification to the patient, more often than not also because of the tireless work of patients-turned advocates. Indiana has passed a law but the language falls short of mandatory patient notification. These events were state-by-state battles, full of angst among all parties, especially early on. Not surprisingly, the early language and final effects vary per state.
A recent article in the Journal of the American Medical Association compared the then 23 states’ notification efforts and found them problematic. The article’s conclusions are that “efforts should focus on enhancing the understandability of DBNs, so that all women are clearly and accurately informed about their density status, its effect on their breast cancer risk and the harms and benefits of supplemental screening.” Although several of the points in the article are valid, I do not think it reasonable to expect one notification letter to do all of that alone in simple, understandable language.
A woman is supposed to discuss the topic with her physicians regarding her particular details and what to do next. However, also important is that women seek other sources of education to balance and fill out what their physicians may or may not fully know themselves, so that they can engage in those informed and shared decision-making conversations that are supposed to happen. These should not be limited to women’s magazine articles with their own inaccuracies, which can be present despite the best of intentions. Look for responsible sources; the websites www.densebreast-info.org, www.breastdensity.info and www.areyoudense.org/about are places to start.
So as you do your homework and ask questions on your own behalf, and find excellent imaging facilities to take care of you, do what you need to do regarding breast care, and then tuck that all away until the next time you should think about it or do something. Add to your understanding and knowledge as opportunities or possible problems arise, but the goal is that breast imaging should not consume your life. Go onto the next thing on your to-do lists, since there are always many for us busy women!
Dr. Jiyon Lee is Assistant Professor of Radiology at New York University School of Medicine. Her educational and training background include Yale College, Yale University School of Medicine and Columbia Presbyterian for surgery internship, Diagnostic Radiology and Women’s Imaging Fellowship.