Episode Transcript
Dr. Andrea Kaster:
One of the things we want to drive home is that if you know you have denser breast tissue and that mammograms are still very valuable – they’re still the gold standard for screening – but we know that there are certain things that we cannot see on them and that it’s important to pay attention to your breast. Know what feels normal for you so that you’re more likely to notice a change. And if you do notice a change, we want you to come in and get it checked out.
Courtney Collen (host):
This is “One in Eight,” a podcast series by Sanford Health. I’m your host, Courtney Collen with Sanford Health News. One in eight women will be diagnosed with breast cancer during her lifetime. So we want these conversations to shed light on awareness, featuring expertise from our Sanford Health providers that could save your life or the life of someone you love. We’re glad you’re here.
In this episode, we are talking about breast density, what it is and why it’s important in your care journey at Sanford Health. Joining me is Dr. Andrea Kaster, a breast health specialist who provides care to patients at the Edith Sanford Breast Center in Fargo, North Dakota. Welcome, Dr. Kaster. Thank you so much for being here.
Dr. Andrea Kaster (guest):
Thank you for having me. I’m glad to be here and talk about this timely issue.
Courtney Collen:
We’re so happy to have your insights and we’ll get started with this question: What is breast density and how is it determined?
Dr. Andrea Kaster:
Breast density is essentially a mammographic finding. And that’s a very important point to drive home, is really we know density based on how the breasts image on their mammogram. And so what it is, is the relative amount of glandular lobular structural tissue, or connective tissue, relative to fatty tissue in the breast.
And so the reason that matters is that the more fibrous tissue and glands and ducts show up white on a mammogram, whereas fatty tissue shows up more gray appearing. And so the whiter the background is, the more dense your breast tissue is essentially on the mammogram.
So cancer shows up white on a mammogram as well and so if you have a very white background, you’re looking for a white mass within a white background.
Courtney Collen:
Why is breast density an important factor in mammograms?
Dr. Andrea Kaster:
So, breast density has two major implications on mammography. One is that it can make it harder to see masses. So like talking about the masking effect of that glandular tissue relative to the fatty tissue. So harder for radiologists to see masses and sometimes then the masses actually have to get bigger before they can be seen.
And then the other thing is, which is not completely understood, is that women who have dense breast tissue do tend to get breast cancer more often. So whether it’s just the relative amount of more active cells in their breasts, there’s not really sure what that connection is, but it is an independent risk factor for breast cancer. So it’s a twofold risk.
Photo by: Sanford Health
Courtney Collen:
OK, good to know. How common is it for women to have dense breasts? Is it common?
Dr. Andrea Kaster:
It is common. And that’s a very good point to make is that actually 50% of women have what would be considered dense breast tissue.
So the American College of Radiology has four categories of density that are given with every mammogram that’s done. And that is a category A, B, C, or D, which means primarily fatty-replaced breasts, scattered fibroglandular changes, heterogeneously dense, or extremely dense breast tissue. And it’s the heterogeneously dense or extremely dense categories that count as dense breast tissue.
So 50% of women fall into one of those two categories on average, it depends somewhat on age, but we would say about 10% of women have fatty-replaced breasts, 40% have scattered fibroglandular changes, 40% have heterogeneously dense and about 10% have extremely dense. So it is not uncommon or abnormal to have dense tissue.
Courtney Collen:
Are there any lifestyle factors that contribute to having dense breasts? Why do some women have more of that dense breast tissue than others?
Dr. Andrea Kaster:
Density is primarily determined by your genetics, just how your breasts were kind of genetically predisposed. So we will see family where, yes, all the women have denser tissue. And so that is the primary reason that we will find dense breast tissue in some women compared to others.
There are definitely other things that go into it. So, you know, genetics is a big deal. As you get older, your breast density tends to go down. So we lose some of the more ductal and the lobular tissue and it’s more fatty-replaced with age.
If any individual has a dramatic change in their weight, that can change their breast density. Pregnancy can make a difference. So pregnant breasts on imaging tend to be much more dense. Menopause with a drop in estrogen will decrease your breast density. If you’re on hormone replacement therapy or hormone blocker therapy, those can either increase or lower your density.
So there are definitely things in our life that can make a little bit of difference, but it’s primarily genetics. And as we go through life, you will look back on a mammogram and you can compare to, and there may be a difference that you see, it’s not a like one year from the other, you’re seeing a dramatic difference unless we add in some of these other factors.
Courtney Collen:
What challenges do dense breasts present in detecting breast cancer through mammograms?
Dr. Andrea Kaster:
We know that the denser the breast tissue is, the whiter the background or the whiter the appearance on a mammogram. And cancers show up white on a mammogram, so if you have a very white background, it’s like a polar bear in a snowstorm. It’s just a lot harder to see a white change within that.
And so we find that cancers are found at a slightly larger size when women have denser breast tissue. They tend to have pathology with some more high risk features related to it. And we know that the sensitivity of the mammogram, meaning the number of cancers found on a positive test, is lower with dense breast tissue.
So whereas a mammogram in a woman who has a very fatty-replaced breast, their mammogram’s going to catch, we would say, and the numbers vary, but we would say a nine out of 10 breast cancers on initial. And that goes as low as 62% or 6.2 out of 10 breast cancers in extremely dense breast tissue. So the difference between the sensitivity of the mammogram is quite a bit.
And so a big take home message for patients is really that we know mammograms are great and a lot of this information that we share with women, because we’ve always talked about density, but it hasn’t always been something we talked about with patients.
But one of the things we want to drive home is that if you know you have denser breast tissue and that mammograms are still very valuable – they’re still the gold standard for screening – but we know that there are certain things that we cannot see on them and that it’s important to pay attention to your breast. Know what feels normal for you so that you’re more likely to notice a change. And if you do notice a change, we want you to come in and get it checked out.
The whole idea behind this started with a woman who was a stage 4 breast cancer diagnosis, and she felt a lump after a mammogram and sort of thought, well, I just had my mammogram, it’s going to be fine. This can’t be anything. And delayed going in with that sort of sense of security.
So for all densities, we want women to report changes, but that’s especially the case knowing in women with denser tissue that the mammograms are just not quite as sensitive as they are for women with less dense breasts.
"Breast cancer is a very common cancer. It's common in younger women and the sooner we can find it, the better options we have for treatment." Dr. Andrea Kaster, Sanford Health
Courtney Collen:
Are there any additional screening methods recommended for women who have dense breasts?
Dr. Andrea Kaster:
Yes, there have been some current guidelines that are suggesting that patients should at least talk to their providers about their density. And talk about if there are supplemental screening options for them that would be useful. So it kind of depends upon the area of the country you’re in or even what Sanford facility that you are going to and what those options are.
For women who have extremely dense breast tissue, or heterogeneously dense breast tissue, and have an increased risk of breast cancer, the best supplemental screening is an MRI. That’s kind of the most well-studied supplemental screen we have. We typically do that at about a six-month interval from the mammogram. So they’re actually, again then getting screened twice a year.
MRIs are a completely different type of study. They’re a magnet and they use a contrast material called gadolinium to look for areas of blood flow changes within the breast. And so they look at things totally differently. They do not replace mammograms. They are in addition to mammograms and so that is a good option for women who are higher risk.
For women who might have dense breast tissue, but don’t necessarily qualify for a breast MRI or to qualify for being higher risk, then we have other options. One of them that we use most commonly is a contrast enhanced mammogram that again, uses a contrast material to highlight any areas of increased blood flow.
Some facilities do whole-breast ultrasound. The sensitivity on whole-breast ultrasound is not as high as some of those other studies I talked about so we don’t use that here. And some do like a molecular test on the breasts as well. But again, that’s not something that we use here. So typically it’s either adding an MRI or a contrast enhanced mammogram.
Courtney Collen:
In talking about risk, which you mentioned a moment ago, how would breast density or how does breast density affect a woman’s risk of developing breast cancer?
Dr. Andrea Kaster:
Like we talked about, it does increase your risk probably about 1.2 to twofold increased risk of breast cancer in women who have denser breast tissue. So it does increase the risk and that is part of the overall picture.
There are many things that can affect your breast cancer risks. Some of them are much more kind of prominent than others. Certainly if you have a history of an early breast cancer yourself, if you’ve had an abnormal biopsy with you know, atypical hyperplasia or LCIS, if you have genes that increase your risk, all family history, that all can make a difference.
And so it really takes doing using a risk assessment tool that includes density as part of your risk in order to determine that cutoff. And typically we would use the cutoff at about 20%. So women whose lifetime risk is above 20% are considered to be high risk, and then there’s kind of a moderate risk category around 15 to 20%. And then the average risk below that.
We currently recommend starting annual mammograms at age 40 based on the fact that that is the way to save the most lives. And so that is our recommendation definitely for women who are identified at being higher risk or say for example, have a mammogram for diagnostic purposes because you wouldn’t necessarily know if you have dense breast tissue unless you’ve had a mammogram because we can only know by the mammogram findings.
And so say somebody comes in with a problem and they get a mammogram and they’re found to have extremely dense breast tissue, that is a patient who we may want to do a risk assessment model on to see if they would qualify for earlier screening. And there are many studies that show that for women who do have extremely dense breast tissue or heterogeneously dense breast tissue in their 40s, that there is a very high benefit to having that annual mammogram.
Some guidelines will say you can go every other year or you can wait till 45. That does not apply to women who have dense breast tissue.
Courtney Collen:
Can you determine dense breasts by like a physical exam or it needs to be determined by a mammogram?
Dr. Andrea Kaster:
It can only be determined by a mammogram. Because it really is, when we’re talking about density in this form, in the technical scientific form, it is the relative amount of fibrous tissue to fatty tissue. And you can’t tell by feeling.
Courtney Collen:
You can’t just touch your breast and say, you know, these feel dense.
Dr. Andrea Kaster:
(Laugh) No, and that’s a very common – I have people tell me all the time that they have dense breast tissue and they’re talking about the way that their breasts feel. Right? Sure.
So what breast density is not, it is not lumpy breasts, it is not firm feeling breasts, it is not size of the breast. All of those things are commonly kind of misconstrued as I have dense tissue because it’s really lumpy. Well, breasts are actually mostly lumpy and that does not have anything to do with what they’re going to necessarily look like on imaging.
Courtney Collen:
What should women with dense breasts know about their mammogram results?
Dr. Andrea Kaster:
I think that they should first of all know some of the things we talked about. Like we just know that it is not considered abnormal to have dense breast tissue. That it’s actually very common.
I think it’s important for them to know that yes, it does increase their risk, but it’s part of the whole picture. And so talking to your provider about what your other risk factors might be in order to get a better whole picture, I think it’s very important for them to know that mammograms still work. They are still considered to be the gold standard for screenings because a lot of times women will come in and think, well, I don’t need to have a mammogram because my breasts are too dense. And it’s like, and that is not the case.
We still want use mammograms as our best screening tool for breast cancer. 3D mammography is important in women who have dense breast tissue. So most facilities now use tomosynthesis or what is more commonly called 3D mammograms. That is really important for women with dense breasts.
So I’d say if you do know you have a denser half of tissue, that it’s very good idea to make sure you’re getting a mammogram where they have 3D mammography because that improves cancer detection rate. And it also reduces callbacks because that’s another very stressful time for women when getting mammograms. And if you have dense tissue, you’re more likely to have that overlapping effect of the tissue. And so 3D really helps with that. So I would definitely tell those women, make sure if you are getting it at a facility that whatever facility that is, that they’re using 3D mammography.
And then just to know that it might change a little bit. So one of the things that can be a little bit frustrating or hard to understand is that density can change from year to year or even radiologist to radiologist. So you could have two radiologists look at the same mammogram and one might give one category and one might give a different category. It’s not that your breast density is different in those different pictures or from, you know, even maybe from year to year. It has more to do with variations in the way that a radiologist actually reads those pictures.
And so you may get heterogeneously dense breast tissue one year and extremely dense breast tissue the next year and it doesn’t necessarily mean that your density has changed. It just means that it can vary slightly on lots of factors essentially. So the big overall picture would be that you’re in that denser half.
And then we talked about reporting changes and not, you know, for everybody not relying that if the mammogram is normal, you can’t have breast cancer. That’s never the case. And so we always want to make sure that you’re still paying attention to your breasts and reporting any changes.
Courtney Collen:
Good to know. Are there any recent advancements or studies related to breast density and mammograms?
Dr. Andrea Kaster:
Yes. There are a lot of ongoing studies. There’s still studies ongoing between using 3D mammography like we talked about, or 2D and also an abbreviated MRIs for screening women with dense breast tissue. So there’s all kinds of research going on how we can best screen these women.
There have been some new recommendations or guidelines. The Mammogram Quality Standards Act, which is through the FDA, in September of 2024 came out with guidelines suggesting that all women be advised of their breast density. So it kind of was state to state for a while and now it’s like, nope, all women need to know what their breast density is when they have a mammogram and that they should discuss supplemental screening with their primary care provider. So those are new guidelines that are pretty specific about that.
We need to be having these conversations and at least discussing options for supplemental screening. As far as the American college of Radiology in 2018, they recommended an annual MRI for women who have had a history of breast cancer and have dense breast tissue. And so that is new related to breast density specifically, new recommendations there.
So there have been these more recent changes. Along with people being more aware of it, they’re giving us guidelines on how to best utilize that information.
Courtney Collen:
It’s such valuable information and really the more that we know about our own bodies, the more proactive we can be about our health. Like now leaving this conversation, I want to know what my breast density is and I should probably wait until I’m 40 to get that mammogram. But no, it’s all fascinating. And we appreciate the update in those advancements and studies.
Dr. Kaster, if a woman is concerned about her breast density or the risk of developing cancer with dense breasts, what would you tell her?
Dr. Andrea Kaster:
So, I mean, I start by trying to make it seem that, to understand that it is more normal than we might realize, so that it’s not a bad thing. It’s not that there’s something wrong or that it’s even that unusual. That we just, it’s just more common than people realize. And so to try to think of it that way. A lot of people are relieved to find out that it’s actually not a rare thing and that there’s more women out there than they might realize.
And then just to talk to their providers about their overall risk because it is part of the picture but not the whole picture. And so that it’s important for them to talk with their primary care providers about if they need to have a more formal risk assessment or if they need to do any extra testing because of that.
And then continue with their breast awareness, continue with their annual mammograms, request a clinical breast exam if they feel like they have dense tissue and want to make sure that they’re getting checked out. That would be important as well.
Courtney Collen:
Well, this has been such valuable information, Dr. Kaster, learning so much about breast density, which is going to be great information for our patients listening.
Dr. Andrea Kaster:
We are here at the breast center anytime people have questions or providers have questions and they want to reach out, we’re happy to discuss this with them. I do think it’s important to have a good discussion about it kind of early on with realizing if you are in that denser half so that people have a good understanding of what the recommendations are going forward.
We will be keeping abreast of all new changes and changes in guidelines and making sure that we keep updating that all the time through our facility and through our Edith Sanford initiative and just making sure that we’re doing the best we can for screening.
We know that screening helps, but we also know that breast cancer is a very common cancer. It’s common in younger women and the sooner we can find it, the better options we have for treatment and the less aggressive treatment that is needed for cures. So it is important to try to find it as early as possible and that takes the whole team working together to do the best we can for women.
Also, just a reminder for patients too, is that you can get breast cancer before 40. So make sure that you’re paying attention to your breasts as well. If you have a family history, reaching out and trying to see if you might be a candidate to start screening sooner is also really important.
Courtney Collen:
So important. Dr. Kaster, thank you so much for all of your information and expertise on this topic and for all that you do for patients at Sanford Health.
Dr. Andrea Kaster:
Thanks for having me.
Courtney Collen:
This episode is part of the “One in Eight” podcast series by Sanford Health. For additional podcast series by Sanford Health, find us on Apple, Spotify, and news.sanfordhealth.org. I’m Courtney Collen. Thanks for being here.
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