Q&A

On Cancer: Diagnostic Radiologist Carol Lee Discusses What Women Should Know about Breast Density

By Media Staff  |  Wednesday, January 30, 2013
Pictured: Mammogram A new law requires radiologists to inform women if dense breast tissue is found on a mammogram.

To help improve breast cancer detection and prevention, New York Governor Andrew Cuomo recently signed legislation that requires radiologists to inform women if dense breast tissue is found on a mammogram. The law, which went into effect this month, is raising awareness among women about this topic.

In an interview, we discussed the concept of breast density with diagnostic radiologist Carol H. Lee. Dr. Lee suggests that if you find out you have dense breasts, you should discuss potential next steps with your doctor. Each individual woman’s risk for breast cancer is different, and many factors – such as family history and lifestyle – must be taken into account when determining whether additional forms of breast cancer screening are necessary.

What are dense breasts?

Breasts are made up of different types of tissue: fatty, fibrous, and glandular. Fibrous and glandular tissues appear as white on a mammogram and fatty tissue shows up as dark. If most of the tissue on a mammogram is fibrous and/or glandular, the breasts are considered to be dense.

Because cancer cells also appear as white on a mammogram, it may be harder to identify the disease on a mammogram in women with dense breasts.

How common are dense breasts?

Breast density is classified into one of four categories, ranging from almost entirely fatty (level 1) to extremely dense (level 4). Dense breasts are completely normal. About half of all women have breasts that fall into the dense category (levels 3 and 4). Dense breasts tend to be more common in younger women and in women with smaller breasts, but anyone – regardless of age or breast size – can have dense breasts.

How does a woman know she has dense breasts?

The only way to determine whether a woman has dense breasts is with a mammogram. A breast exam cannot reliably tell whether a breast is dense.

What does having dense breasts do to a woman’s risk for breast cancer?

If you compare the 10 percent of women who have extremely dense breasts with the 10 percent of women who have very little breast density, the risk for breast cancer is higher in those with very dense breasts.

However, most women fall somewhere in between in terms of breast density, so it’s nearly impossible to determine whether a particular woman’s breast density is a risk factor for the disease.

What should women who are told they have dense breasts do?

Women found to have dense breasts should talk to their doctors about their individual risk for breast cancer and together decide whether additional screening makes sense.

Tests such as ultrasound or MRI can pick up some cancers that may be missed on a mammogram, but these methods also have disadvantages. Because they are highly sensitive, they may give a false-positive reading, resulting in the need for additional testing or biopsy that turns out to be unnecessary. There is also no evidence to show that using screening tests other than mammography in women with dense breasts decreases the risk of death from breast cancer.

Ultimately, women who have dense breasts should weigh the pros and cons of additional screening with their doctor.

Should women who do not have dense breasts make any changes to their regular screenings?

Women who do not have dense breasts may still develop breast cancer, and should continue to receive regular mammograms. Regular mammography is the only screening method that has been shown to decrease deaths from breast cancer, and all women of appropriate age should have mammograms, regardless of their breast density.

Memorial Sloan Kettering provides comprehensive, individualized breast cancer screening services that include mammography, ultrasound, and MRI, through our Breast Screening Program, located in Manhattan.

Comments

It was always my understanding that dense breast tissue simply made it more difficult to detect a cancer should it occur. The above comments would suggest that density itself increases cancer risk. Is this true? By what mechanism? Can you provide references? Thank you.

Thank you for your comment. We spoke with Dr. Lee, and she said that it is generally agreed that women with dense breasts are at increased risk for breast cancer. For example, the 10 percent of women with extremely dense breasts have four to six times increased risk compared to women with mostly fatty breasts. However, most women fall between these extremes, and it is nearly impossible in any given woman to determine her level of risk based on the mammogram alone. The mechanism by which density is associated with risk is that breast density can be caused by glandular tissue, which is the tissue in which most breast cancers arise. Therefore, the more glandular tissue, the more the risk. It is also very important to understand that women with non-dense breasts can develop breast cancer. A reference discussing mammographic density and breast cancer risk is in the Journal of the National Cancer Institute 2012;104(18);1345.

I was wondering if breast feeding has an effect on a woman's breast density in the long-run? Apparently, recent research has shown that breast feeding can help to lower a woman's risk of developing breast cancer, but I was curious about the underlying factors that could play a role. I read about this in a really intriguing article which is available at: http://www.knowcancer.com/blog/recent-breakthroughs-in-breast-cancer-research/

Thank you for your comment. Dr. Lee says that most studies have found that breast feeding is associated with an eventual decrease in breast density, but other studies have indicated that there is no significant difference in density among women who have breast fed compared to those who have not. There does seem to be a decreased risk of breast cancer associated with having breast fed, but the mechanism by which this occurs is not fully understood.

I was recently dx with breast cancer, but my mammogram was negative secondary to high density. The cancer was found initially in my lymph nodes and the primary site was found on guided US. I was never told that I had high density mammograms in the 25 years I have had annual mammograms. My mother had breast cancer. I am now surprised and upset that none of my doctors ever recommended other breast screening, considering my history. It may have been found before it had a chance to travel to my lymph nodes. Surgery revealed that i had 16/21 positive nodes.

My sister has been diagnosed with Stage 1 breast cancer in one breast. Subsequent to the discovery of cancer, she had a followup MRI of both breasts to determine whether or not "something was missed" by the ultrasound and previous mammogram. There was, in fact a "suspicious" area in the second breast, revealed by the MRI that required a followup MRI biopsy, which proved negative. I wonder how frequently this scene is played out in cases where further testing involves MRI, and whether some other test might be better suited as a diagnostic tool (or is this all there is, aside from ultrasound?), given the extreme sensitivity of the MRI. Incidently, my sister was told by the surgeon that she has dense brest tissue.

I have early Stage 1 infilitrating lobular carcinoma in one breast caught by mammogram. 1 cent. or smaller. I am contemplating double masectomy even though told that lumpectomy plus radiation and arevidex. Some people have told me that a masectomy may result in the ILC returning in the bone because there is no more breast tissue. Could this be so. Thank you

Thank you for your comment. Unfortunately, we are unable to answer personal medical questions on our blog. To make an appointment with a Memorial Sloan-Kettering physician, please call 800-525-2225.

I have found this information very useful. I'm in remission from Stage 3 Triple Negative Breast cancer. I wish my doctors had explained to me that I had dense breasts. This was told to me after the fact of being diagnosed with cancer. I would have understood why I should have sought tx from a breast specialist sooner!! I think the new law should help women who are in same situation as I was to be more informed which in turn may prompt them to go to breast specialist sooner resulting in increased early stage detection. Way to go Governor Cuomo!

My cancer was discovered by ultrasound and did not appear on mammo. When mammo was performed in January of this year breast density was evident but I was told no follow up to notification was provided in NY law and therefore insurance companies may not cover follow up such as ultrasound. Is this true? what happens if same cancer comes back and is not discovered on mammo?

Unfortunately we are not able to answer personal medical questions on our
blog. We recommend you speak with your doctor and your insurance company
about what follow-up may be needed and whether or not it would be covered
under your plan. If you'd like to speak with a doctor at Memorial
Sloan-Kettering, please call 800-525-2225. Thank you for your comment.

How much of the increased risk of breast cancer in a dense breast, comes from having to get a higher dose of radiation from screening mammogram to penetrate the breast tissue do you think? Is there any evidence that radiation exposure in breast feeding (when breasts are denser) carries a higher risk of breast cancer?

Hi Laura, we spoke to Dr. Lee who said, "The association of density and risk is a complicated subject. With regard to radiation during mammography, the amount of radiation that is needed depends on the density of the tissues as well as on the size of the breasts.

It is quite possible that a woman with large breasts that are not dense would get more radiation during a mammogram than a woman with small, dense breasts. However, it is unlikely that this difference in radiation dose would significantly contribute to the risk associated with dense tissue.

With regard to radiation exposure during breast feeding, I am not aware of any specific studies but we do not generally do mammograms when a woman is breast feeding, because mammograms are less helpful during that time. We rely mostly on ultrasound in that setting."

Thank you for your comment!

I had 2 mammograms this yr due blood discharge from my left breast. One in January 2013 and one in August 2013 along with ultrasound. All those came back neg. for breast cancer however, my Dr wanted to see an MRI of both breast because I had breast cancer 20 yrs ago on my right side. But my MRI came back with neg. for cancer but my breast was diagnosed with having extremely dense background and its hard to determine they said. So what would be my next step I am worried and anxious to know more because I am not satisfy with all these answers I am getting. I know that something is wrong with my left side and right side as well but they are not able to find anything, please help with some advise.

Renee, unfortunately we are not able to answer personal medical questions on our blog. If you'd like to make an appointment to speak with a Memorial Sloan-Kettering doctor, you can call 800-525-2225 or go to http://www.mskcc.org/cancer-care/appointment for more information. Thank you for your comment.

both of my ultrasounds and mammo came back neg. for breast cancer, but only my mri came back with extremely dense breast. What does this mean? I had cancer in 1993 DCIS of the right breast only. So do I have to do more test?

Renee, we are unable to answer specific medical questions on our blog. If you would like to make an appointment with a Memorial Sloan-Kettering physician, please call our Physician Referral Service at 800-525-2225 or go to http://www.mskcc.org/cancer-care/appointment. Thanks for your comment.

I recently had a major change in br east de..nsity. About 2/3rds on both breast .nurse actually asked if I have implants! The lower bre a.st tissue is normal. Im43 and my breast have never LOOKED better. CAn I keep them. ? No job or insurance. Dr. Wants me to get second mamo and ultrasound. I can't afford to re exact test three days later!!! Why !!? Unclear results or test performed diffrently!!? Then.....ok. say I do have it in bothboobies and armpit. Cannot.afford treatment and now have pre existing condition

Heather, we are unable to answer specific medical questions on our blog. If you would like to make an appointment with a Memorial Sloan-Kettering physician, please call our Physician Referral Service at 800-525-2225 or go to http://www.mskcc.org/cancer-care/appointment. For general cancer-related questions, you also can call the National Cancer Institute’s Cancer Information Service at 800-4CANCER (800-422-6237).Thanks for your comment.

Today, I had my annual mammogram along with an ultrasound. I was told that my breasts were very dense. I received the new notification about breast density as well. There is no history of breast cancer in my family as far as I know, but the radiologist said to follow up with my GYN. What are my risks? Should I consult with my GYN asap? Thanks

Elizabeth, unfortunately we are unable to answer specific medical questions on our blog. You can follow up with your GYN. If you would like to make an appointment with a Memorial Sloan-Kettering physician, please call our Physician Referral Service at 800-525-2225 or go to http://www.mskcc.org/cancer-care/appointment. Thanks for your comment.

Does fibrous glandular tissue show up in ultrasounds?

Dear Carla, we sent your question to Dr. Carol Lee, and she provided the following response:

"Dense fibroglandular tissue does show up on ultrasound but unlike mammography, it has a different appearance from most masses that are seen on ultrasound, both benign ones and malignant ones so it is often easier to find masses that are in dense tissue on ultrasound than it is on mammography."

Thank you for your comment.

Do African American women tend to have denser breasts than white women and could this contribute to delayed diagnosis and increased mortality among black women with breast cancer? Thanks.

Jennifer, thank you for your comment. We forwarded your question to Dr. Lee, who responded, "Overall, African-American women do not have higher breast density than women of other races so this does not seem to be a factor in the higher mortality rates among this population of women. Other factors such as decreased access to care and more aggressive tumor types may be contributing to the situation."

Could you please tell us how someone with dense breasts would know if they have glandular or fibrous breast tissue?

Dear Marion, we recommend you discuss that with your physician. For your information, here is a patient education summary with information about breast density and breast cancer screening that may be of interest: http://www.mskcc.org/cancer-care/patient-education/resources/breast-density-breast-screening
If you would like to make an appointment with a Memorial Sloan-Kettering physician, please call our Physician Referral Service at 800-525-2225 or go to http://www.mskcc.org/cancer-care/appointment.
Thank you for your comment.

Is it possible if in mammogram and ultrasound cancer is not found because of dense breast It will show in an MRI ?

Dear Donna, we sent your question to Dr. Lee, and she responded:
"Yes, it is possible. There was a large study done where women with dense breasts and increased risk for breast cancer had both screening mammograms and screening ultrasounds that were negative. They went on to have screening MRI and a few additional cancers were found. There are downsides to MRI, however, and it is not suitable for everyone. Which test or which combination of tests is best for any individual should be decided after discussion with a person's doctor."
Thank you for your comment.

What percentage of the time is a diagnosis made based upon the mammogram and/or ultrasound vs. needing additional tests or a biopsy for a definitive diagnosis? I understand it's given that a diagnosis could lead to additional tests and treatment, but I was just wondering if the diagnosis can be made just from the mammogram and ultrasound?

Dear Krista, we sent your question to Dr. Lee, and she responded: "The diagnosis of breast cancer is always made by biopsy, often done with a needle. Occasionally, the mammogram or ultrasound appearance can be very suspicious but the actual diagnosis must be made from tissue analysis." Thank you for your comment.

I am curious to know if MRI or mammogram can occur while a woman is breastfeeding, particularly in the case of a woman who is Brca positive. Thank you.

Hi Maria, we consulted with Dr. Lee, who provided this response to your question:

Mammography and MRI can be done while a woman is breastfeeding but the accuracy of both of these tests is reduced because the changes that occur with breastfeeding make cancers harder to see. For routine screening, it is generally preferable to wait a few months after breastfeeding has stopped before doing a mammogram or MRI.

In these studies finding a higher risk of breast cancers among women with dense breasts, how can one rule out the possibility that dense breasts have more breast tissue that can be exposed to the radiation from mammograms, which can, in turn cause malignancies? What is the latency period for this type of radiation exposure? Also: Was the number of previous mammograms controlled for? Can we know whether a woman confers a higher risk even if she doesn't undergo frequent mammography?

Chris, thank you for your comment. We consulted with Dr. Lee about your questions and this is her response:

The amount of extra radiation delivered to a dense breast compared to a fatty breast is extremely small and there are some situations where a woman with a large, less-dense breast gets more radiation than a woman with a smaller but denser breast. A recent study from Massachusetts showed that most women who died from breast cancer either had never had a mammogram or had not had one in years. Having a regular mammogram, whether your breasts are dense or not, decreases the chance of dying from breast cancer. The increased risk associated with dense breasts does not seem related to the number of mammograms a woman has.

My mother and I both have very small breasts--32AA. My mother recently had a mammogram and was told that she has Level 4 dense breasts. I got very worried and encouraged her to ask for follow up tests, but she doesn't want to. She seems to think that because of how small our breasts are, there is no way that we could have enough fatty tissue to have breasts that aren't considered dense. Is there any validity to that? We are of East Asian descent and I've been told that increases the chances of having dense breasts but decreases the risk of breast cancer.

Hi Jane, this type of specific question should be discussed with your mother's physician as we are unable to answer personal medical questions. As Dr. Lee recommended in the Q and A: "Women found to have dense breasts should talk to their doctors about their individual risk for breast cancer and together decide whether additional screening makes sense."

Thank you for your comment.

My older sister (by ten years) was just diagnosed with DCIS. She is waiting after the holiday to an oncologist and breast surgeon. Our mother passed away at age 84 of melanoma. No family history of breast cancer. I recently had a mammogram, no cancer. A couple of years ago, I had an ultrasound, due to dense breasts/some calcifications, with negative results. I was told there was no need for a biopsy. Do you suggest I request another mammogam, in light of my sister's situation, or should I just wait for my annual mammo in a few months? My sister is 10 years older than I am.

Dear Ms. Finelli,
We are sorry to hear of your sister's diagnosis. Unfortunately, we cannot answer personal medical questions on the blog. You may be interested in referring to our breast cancer screening guidelines for more information: http://www.mskcc.org/cancer-care/adult/breast/screening-guidelines-breast
If you are interested in making an appointment with one our specialists for a consultation, please call our Physician Referral Service at 800-525-2225. Thank you for your comment.

I am 51 yr old that had mri of shoulder due to surgergy and part of my mri result was partially imaged, ovoid area of heterogeneous but predominately increased T2 signal in right breast. Differential considerations include glandular tissue and breast mass. Had mammo and was told to wait 6 months for recheck.... is that normal?

Dear Jane, unfortunately we are unable to answer personal medical questions on our blog. If you would like to make an appointment with one of our specialists for a consultation, please call our Physician Referral Service at 800-525-2225. Thank you for your comment.

when a lump is found to be a dense tissue lump & negative via mammo & untrasound, is it prudent to get a needle biopsy or lump removal? what would the pros & cons be? thanks

Hi Felicia, this type of specific question should be discussed with your physician as we are unable to answer personal medical questions. A lot of factors, such as family history would come into play. As Dr. Lee recommended in the Q and A: "Women found to have dense breasts should talk to their doctors about their individual risk for breast cancer." If you would like to make an appointment with a Memorial Sloan-Kettering physician, please call our Physician Referral Service at 800-525-2225 or go to http://www.mskcc.org/cancer-care/appointment. Thanks for your comment.

I am currently nursing down to only 2 times a day. I had both my babies in my 40's so my last mammogram was a baseline at 36. I have been worried about breast cancer since I've had chronic back and shoulder pain for 4 months. I went to my doctor who performed a clinical exam and had a breast ultrasound which didnt show anything worrisome. Is a negative ultrasound a reassuring thing that things are ok? I don't really want to stop nursing yet which I know is needed for a mammogram.

Cathy, unfortunately we are unable to answer specific medical questions on our blog. If you would like to make an appointment with a Memorial Sloan-Kettering physician, please call our Physician Referral Service at 800-525-2225 or go to http://www.mskcc.org/cancer-care/appointment. Thanks for your comment.

I had a mammogram just last week and the results says all fat in the tissue, but my last one about a year and a half ago said very dense tissue. Can it change that quickly from one extreme to the next?

Sharynn, we are unable to answer specific medical questions about individual cases on our blog. You might call the National Cancer Institute’s Cancer Information Service at 800-4CANCER (800-422-6237). If you would like to make an appointment with a Memorial Sloan-Kettering physician, please call our Physician Referral Service at 800-525-2225 or go to http://www.mskcc.org/cancer-care/appointment. Thanks for your comment.

I had my first mammogram last year & 2 weeks later I was contacted by phnom telling further testing was needed. I went back in & another mammogram of right breast was performed. After waiting about 30 minutes they sent me over to have ultersound done as well on the right breast. They told me that my right breast was very dense so they needed different imagining done. I was also told ther was 2 different findings in my right breast that they wanted a better view of. A week later I received a letter stating that it was Benign but they wanted to keep an eye on it & for me to come back in 6 months to see if there was any changes in either place. Well I just recently went back & my chart stated I was to have ultrasound & mammogram on right breast but they only did the mammogram. I just got letter today from them stating that there was findings on my right breast from my recent mammogram & that it appears to be Benign not cancer & it showed very little change. Also that I needed to return in another 6 months and have a bilateral mammogram done to confirm that nothing hasn't changed. Well my question is how can they be certain it's Benign & if it is why do I need to come back in another 6 months & would it not make more sense to have biopsy? Thanks so much in advance for any answers or help you can offer to me!

Unfortunately, we are unable to answer specific medical questions on our blog. If you would like to make an appointment with a Memorial Sloan-Kettering physician, please call our Physician Referral Service at 800-525-2225 or go to http://www.mskcc.org/cancer-care/appointment. Thanks for your comment.

I am 51 years old and have been told I have "very dense breasts" since my first mammogram (when I was in my late 30's). I've been told that decreasing my caffeine intake and taking Vitamin E can help reduce this problem. Is this true? If so, how much Vitamin E should I take a day?

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