There's been a lot of discussion recently about women with dense breasts and hiding cancers and the potential need for adding additional screening tests and also some new rules that will be coming out from the FDA, and I wanted to talk with you all about that.
We know that mammography alone works pretty well. We should start screening every woman at least by age 40 if she has an average risk of breast cancer, and we find about 5 cancers per thousand women screened. Overall, about 10% of women, or 10 to 100, will be called back for additional testing, but only 5 of those women will have cancer, which means that most of the time, 95% of the time when we're called back for those additional views, there will be no cancer.
And it's important not to be overly worried until we have the additional imaging done. But there is an issue of breast density that we need to be aware of. There are 4 categories of breast density, and I will talk more about that, but you can see on the left a fatty (tissue) breast, which is mostly the darker gray.
And the cancer with the yellow arrow is easy to see. But in the right-hand image, this is the woman with dense breasts, and the cancer is actually pretty hard to see, even though it's palpable and we can just see it at the edge of the breast, and it's a much larger cancer. Here are the 4 categories that we use to describe breast density.
All this information should always be in the mammogram report. And it should say either category A, which is fatty (tissue) breast, or category B, which is scattered follicular tissue. And you can see this cancer moving into those breasts. They're pretty easy to see. But it is hard to find cancer in breasts that are dense in different ways or that are very dense.
And even in a scattered breast, if it happens to be in an area where there is dense breast tissue, it could still be missed on the mammogram. And this really is the issue that we all need to be aware of. Most of us fall into one of these categories somewhere in the middle between scattered and heterogeneously dense. Approximately 80% of women fall into one of these two categories.
Only about 10% of women have fatty (tissue) breasts or extremely dense breasts. And overall, if we look at the combination of heterogeneously dense and extremely dense, that represents about 40%, or 40 to 50%, of all women. As we go through menopause, the breasts tend to be a little less dense. We lose some dense breast tissue density.
But still, about a quarter of women will be dense even into their 60s. And that's where we have some issues with hiding cancer. 3D mammography or tomosynthesis can help by slicing through the dense breast tissue. And as you can see, maybe we see another 1 to 2 cancers per thousand women screened with tomosynthesis.
I have this sort of rule for my forties, and that is that all women should start getting mammograms by age 40. Getting mammograms reduces the breast cancer risk and of dying from breast cancer, risk of breast cancer by about 40%. And we'll talk more about why we don't do more than that. About 40% of women with dense breasts, and about 40% of cancers are hidden or missed in dense breasts on a mammogram.
This map from the website I work with shows breast density notification laws, which are some kind of law in effect in 38 states plus the District of Columbia. The first law was passed in Connecticut as part of the work of Nancy Capello and other advocates. Joann Pushkin works with us on the website, and she passed the law in New York.
The issue is that even though there are, I think, 90% of women in the country covered by some sort of breast density notification, these laws actually vary in what they tell the patient. Some laws require us to tell a woman she actually has dense breasts, but other laws, like in Connecticut, only require her to receive information saying that breast density can hide cancer.
But she may not be told that her own breasts are dense, and this is one of the issues. A new regulation that's required by the Food and Drug Administration should address this. Actually, in 2019, this was part of the Federal Budget Act that required the FDA to develop a new standard at a national level that will in fact require all mammography facilities to include a new standard in the results letter that goes to the patient to tell her whether or not her breasts are dense. In fact, whether she has, excuse me, heterogeneously dense or extremely dense breasts may or may not be included, but at least if it says she has dense breasts, she's in one of those categories. Then there's the serious issue of cancer being hidden on the mammogram and going undetected. And then you may want to talk to a doctor about additional screening.
So let's go through some of these issues in a little bit more detail. and surveys About 2/3 of women who know about their breast density are aware that it can hide cancer and that it also increases risk of breast cancer. But only about 2/3 of the women surveyed were actually aware of breast density as an issue at all.
And here, this slide just shows how breast density also increases breast cancer risk. I like to think of it this that if in a fatty (tissue) breast, there's very little glandular tissue, and cancer develops in the area of glandular tissue. And that's part of why we have a higher risk of breast cancer with the increase of dense breast tissue.
It's on the order of a 4–6-fold higher risk in an extremely dense breast compared to a fatty breast. Again, most women fall in the middle, or so some people say, since the average woman has at least some scattered. Figo tissue (dense breast tissue) that the increased risk of breast cancer from breast density is only about a 2-fold risk.
And that's another way to look at this. But in any event, it does increase risk, and it is now part of the risk models that are used to estimate risk and determine who should have additional breast cancer screening. There are several types of supplemental breast cancer screening that are worth talking about. Ultrasound and MRI are by far the most widely available.
With ultrasound, of course, there's no contrast injection, and there's no ionizing radiation. It can be a mammogram and have a more advanced stage of diagnosis.
Ever since 2007, there's been a recommendation to do an annual MRI in those women starting at age 30, and again, I'll talk more about that. With an MRI, it does require lying on this table with your breasts hanging into the coils. The red arrows show the coils, and some women are claustrophobic and don't tolerate that positioning.
It's not very comfortable. It does require intravenous contrast, which is a gadolinium type contrast. It is known that gadolinium builds up in the brain, but that doesn't seem to hurt anything. But that is a little bit of a question mark out there, and it's not something that we are all thrilled about.
But I think it's just that we can detect that it probably doesn't really cause any harm. MRI is a rather expensive test that is not widely available. It may be that you can get an abbreviated MRI at some centers where you would pay out of pocket for this exam, anywhere from $200 to $600.
But most centers would have what's called a diagnostic protocol MRI, which takes upwards of 30 minutes to perform and would be built to insurance specifications that may not be fully covered. I know for myself that it ends up being about $250 after insurance, but it varies a lot depending on your deductible and copay situation.
With MRI, we do have the highest additional cancer detection rates, on the order of 10 to 16 per thousand. In the first round, it's up to about 7 per thousand on an annual basis. Thereafter, it does not use any ionizing radiation. And it has been shown to greatly reduce, if not eliminate, interval cancers, late stage disease, and find very early breast cancers that are easily treated.
About 2/3 of the cancers seen on MRI are invasive cancers, and about a third of them, up to a third of them, are actually ductal carcinoma. In situ, it tends to find the higher grade DCIS, and it is felt that these are the biologically more important cancers that we find with MRI, so that's also encouraging.
And then, finally, contrast enhanced mammography looks very promising. This is something that can be done in a standard mammogram suite with the same equipment and same positioning as regular mammography. But the equipment has to be upgraded to have this functionality. This can be done at a very low cost, and it has a very high yield of finding additional cancers on the order of 10 per thousand.
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And that seems to hold up every year, but this is some of the research that I'm doing right now. This does require an injection of I donated contrast, the same contrast that we use in a CT scan. It makes you feel warm all over, almost like you're going to pee yourself. It's kind of an uncomfortable feeling.
About 1% of patients do have some mild allergic reaction, usually limited to a hive or 2, but it does mean that we have to have our staff trained in contrast reactions, and a physician has to be on site to monitor the exam. As a general rule, they're easily treated reactions with a very small risk of having a severe anaphylactic reaction.
About 2 to 5% of women, depending on their starting risk category and age, will end up with an enhancing finding that's suspicious but turns out to be benign when we biopsy it. So there are false positives, and there is a slightly greater radiation dose from this than from a standard mammogram because we take the low energy and high energy exposure and then subtract that.
But the overall amount of radiation is still well below. Any threshold for concern about causing cancer? As I mentioned, it's not yet widely available, but this looks like something that will become more widely available rather quickly. It is currently only approved for diagnostic use, but it can be performed as a diagnostic mammogram at centers that have this technology.
I mentioned that The American Cancer Society recommends an annual MRI for women who are at high risk. And really, one of the issues is that all women should have some sort of risk assessment, at least by the age of 30, and they may also benefit from genetic testing depending on their risk assessment. We know that women who have a disease-causing mutation should generally start breast cancer screening with MRI at least by age 30 and possibly by age 25, especially for BRCA1 or TP53.
And they started adding mammography as well, by age 30, for women who are suspected of being a pathogenic mutation carriers. For example, if their sister or mother has a known disease-causing mutation but they haven't been tested, they would also qualify for an MRI based on this guideline. And then a broader category where it's a little more challenging is women who are estimated to have a lifetime breast cancer risk of at least 20 to 25%.
There are a variety of models that can be used, but none of these. Terribly simple, the Tyrer–Cuzick model is the most accurate, but still misses a good number of women who will develop breast cancer. And there are some AI models that are being tested to do a better job of this than mammography alone.
So I'm hoping that in the next few years, this will be something that gets a lot simpler to identify the women who are at higher risk and who should have an MRI. You should not use the GAIL model or the BCSC model to do this because they do not consider the age of the relative's prior diagnosis.
The final group is women who've had prior chest radiation, usually for Hodgkin's disease before age 30 and at least 8 years earlier. Those women have a similar elevated risk, comparable to having a pathogenic disease-causing mutation. And finally, I wanted to bring up my own history with breast cancer, especially for this group.
We know that women who've had breast cancer in the past have had more cancers missed on mammography. Even when the breasts are not dense, this may be in part due to scar tissue or other (breast cancer risk) factors, and they're also obviously at a higher risk for having a second cancer or recurrence. The current recommendations are based on several large studies that have been done, including having an annual breast MRI if the women with dense breasts, have a personal history of breast cancer risk, or if she was diagnosed by age 50, even if she doesn't have dense breasts, because those women are more likely to have recurrence and also to benefit from the breast cancer screening MRI.
They suggest considering an MRI for women who have a personal history of breast cancer diagnosed at a later age but have dense breasts. Or if women have prior lobular carcinoma in situ, it's also suggested that they consider an annual MRI then. If a patient cannot access an MRI, can't have it for other reasons, or can't tolerate it for claustrophobia reasons, then ultrasound should be considered for those women.
The NCCN guidelines actually say, "Consider ultrasound or CEM contrast-enhanced mammography for women who qualify for but can't have an MRI.” So it's really important to be aware of these guidelines and to try to follow them in order to really identify cancers as early as possible when the treatment is as simple as possible.
Just a final post-note on that: imaging surveillance of the reconstructed breast after mastectomy is not recommended. This sometimes comes up from patients who request an MRI, even though they've had bilateral reconstruction, and that's not something that's recommended. Supplemental screening should also not continue indefinitely.
even for the highest-risk women with a known BRCA1 or 2 mutation. We do not recommend an annual MRI beyond age 70 or 75. Depending on their overall health, and then finally, I just wanted to mention there is a new guideline in Europe, and this is based on the dense trial that was performed in the Netherlands as well as data from the ECOG-ACRIN 141 study, where they did screening MRI on women with dense breasts in the Netherlands.
They invited women with extremely dense breasts to have an MRI every other year. And this was after a normal mammogram. They found a big rise in the number of cancer diagnoses, which is similar to the rates I mentioned before. On the order of 10 to 13 per thousand, and even in the second round of that screening, they found another 6 to 7 cancers per thousand.
They also were able to show a greatly reduced interval cancer rate of only 0.5 per thousand, compared to 4.5 per thousand for the women not getting an MRI. Based on those findings, they in addition to mammograms, doctors now recommend that women aged 50 to 70 get MRI screenings.
Every 2 to 4 years, in fact, because the MRI performs so much better than the mammogram and there's very little benefit to adding the mammogram, they actually suggest that the MRI could even be done as a standalone, standalone test by itself. For women with heterogeneously dense breasts and no other (breast cancer) risk factors, it's complicated.
Right now, we don't have very clear guidelines. It's certainly important to consider other risk factors like family history, and if a woman meets the criteria for an MRI, she should have one. We do know that as many as 25% of cancers are missed in women with this type of breast density. That's even after 3D or tomosynthesis.
And they really, at this point, would have the option to add screening with ultrasound. If their physician writes a script for it, they would still want to check with their insurance company, and as I mentioned, it's usually covered but subject to a copay or deductible. And at this time in the national picture, it's very much a patchwork in terms of insurance laws.
Again, patient advocates, including Joann Pushkin, who is involved with the website, and other advocates, have been able to pass laws in several states. Overall, 13 states plus the District of Columbia have laws requiring insurance coverage. Supplemental screening with either an MRI or an ultrasound is also available, though in all but New York and Illinois, at the present time, these are still subject to a co-pay deductible.
Pennsylvania is in the process of passing a similar law where the copay and deductible would no longer apply. It's been passed unanimously in the state senate, and hopefully this will be enacted soon. Vermont and Arkansas are the only two states where insurance must cover ultrasounds, but there is a co-pay deductible. In Oklahoma, diagnostic breast imaging is required to be covered, and we don't really know yet because it is just taking effect, I think in November 2022.
Whether that would actually result in coverage for an MRI or ultrasound is unclear because technically those are diagnostic CPT billing codes, even though they're done as a screening exam. So it's not really clear whether that law will cover supplemental screening in Oklahoma. Lastly, Connecticut Representative Rosa DeLauro plans to introduce the "Find it Early" bill in the next week or so. This bill will require a national standard for insurance to cover additional screening with ultrasound, MRI, or other tests recommended by the NCCN guidelines or the American College of Radiology.
Appropriate: This criteria is appropriate. I think this bill is very well written, and I have been fortunate to be able to contribute to the language in it, along with Joann Pushkin from Dense Breast Info. And the easiest way to contact me if you have any further questions would be through the website, densebreastinfo.org.
I mentioned that I am doing some research on contrast enhanced mammography. At this time, I am fortunate to have funding from the Breast Cancer Research Foundation. to invite women who have a family history of breast cancer to get screened with both tomosynthesis and contrast-enhanced mammography every year for 3 years.
We're about to report some preliminary results at the RSNA in 2022, and the results so far have been very encouraging, so I'm hopeful that this will soon become something that will be an option for more women in the future. Thank you for your attention.
Wendie Berg, MD, PhD, FACR, FSBI - About The Author, Credentials, and Affiliations
Professor of Radiology Wendie A. Berg, MD, PhD, FACR, is well-known for her role as study chair and PI of ACRIN 6666, Screening Breast Ultrasound and MRI in High-Risk Women. Dr. Berg got her MD and PhD (in pharmacy) from the Johns Hopkins University School of Medicine, where she also completed her residency in diagnostic radiology. She contributed to the BI-RADS Ultrasound and Mammography Lexicons, has produced or co-authored over one hundred peer-reviewed publications, and co-wrote and edited all three versions of the book Diagnostic Imaging: Breast. She has led and published the results of multicenter clinical trials evaluating breast PET and shear-wave elastography and is currently completing a prospective multicenter study of screening ultrasound after tomosynthesis in women with dense breasts as well as beginning a prospective study of contrast-enhanced mammography versus tomosynthesis in women with a personal history of breast cancer. The website www.densebreast-info.org has Dr. Berg as its chief scientific advisor.