Dense breasts on mammogram? Don’t be afraid.

Only in America can we find a way to scare the bejesus out of a woman with normal breasts and a normal mammogram. Because that’s exactly what happened when New York Times reporter Roni Caryn Rabin read her entirely normal mammogram results letter: “A sentence in the fourth paragraph grabbed me by the throat. ‘Your breast tissue is dense.’”

I can’t really blame Rabin for being afraid. The information about breast density in her mammogram letter was mandatory verbiage crafted by legislators as part of a law that all women be told if they have dense breasts on mammogram:

Your mammogram shows that your breast tissue is dense. Dense breast tissue is very common and is not abnormal. However, dense breast tissue can make it harder to find cancer on a mammogram and may also be associated with an increased risk of breast cancer. This information about the result of your mammogram is given to you to raise your awareness. Use this information to talk to your doctor about your own risks for breast cancer. At that time, ask your doctor if more screening tests might be useful, based on your risk. A report of your results was sent to your physician.

Raise awareness? More like raise the alarm. The information mandated by the law is just enough to scare any women who happens to have dense breasts, but not enough to help her understand what this really means.

If you’ve gotten a letter telling you your breasts are dense, don’t be afraid. Having dense breasts is entirely normal, especially if you are under age 60.  Here’s what you need to know.

What is breast density?

Breast density is a radiologic assessment of how well x-rays pass through the breast tissue. It is a surrogate for how much of the breast is composed of glandular tissue and how much is fat. The radiologist reading the mammogram classifies the breast composition as one of the following:

  • almost entirely fat (<25% glandular)
  • scattered fibroglandular densities (25-50%)
  • heterogeneously dense breast tissue (51-75% glandular)
  • extremely dense (>75% glandular)

Breast density is subjective.

Different radiologists may give the same mammogram different ratings. Use of computerized density measurement could alleviate inter-observer variability, but there is not yet a standardized computer rating system. For the purposes of the law, dense breasts are defined as those that are heterogeneously dense or extremely dense.

Breast density can vary across a woman’s menstrual cycle and over her lifetime.

The same women being scanned at a different time of month or at a later year can land into a higher or lower breast density category, and may or may not get that extra statement in her mammogram letter. Recent research suggests that a single breast density reading may not be the best way to predict breast cancer risk, and that the risk may be confined to those women whose breast density does not decrease with age.

Dense breasts are extremely common, especially in younger women.

According to a recent report of mammograms here in New York City, 74% of women in their 40s, 57% of women in their 50s, 44% of women in their 60s and 36% of women in their 70s have dense breasts.

Increased breast density may be a risk factor for getting breast cancer. 

The mechanism is unknown, but it may be that breast density is just the end result of other factors that increase breast cell proliferation and activity — factors like genetics and postmenopausal hormone use.

How much of a risk? Well, it depends on what study you read and who you compare to whom. If you compare the two extremes of breast density in older women, those with extremely dense breasts have a three to five-fold higher cancer risk than those with mostly fatty breast. The risk is lower than that in those in the middle category of breast density and in younger women, though not well-defined.

The truth is, we really have no way to translate individual breast density into individual risk. Researchers are trying to see if breast density can be incorporated into current risks assessments such as the Gail Model, but at this point, breast density has not been shown to add much more than we already know about a woman’s risk from using these models.

The problem with breast density as a risk factor is that most women at some point in their lives have dense breasts. Should we really consider 75% of women in their 40′s to be at increased risk for breast cancer?

I don’t think so.

Dense breasts can obscure a cancer on mammogram.

This makes mammogram less reliable in women with dense breasts. Digital mammograms may be better at finding breast cancers in women with dense breasts who are also perimenopausal or less than age 50, but it is not known if this translates into better outcomes. Additional testing with ultrasound and MRI can find cancers that mammograms miss in women with dense breasts. Unfortunately, breast ultrasound and MRI screening tests are less specific than mammograms – three times as many biopsies will be done, most of which will not be cancer.

Breast cancer patients with dense breasts are not at increased risk of death compared to those without dense breasts.

In a study of over 9,000 women with breast cancer, no association between increased density and death from cancer was found. In fact, it was obese women with lower breast density who had the higher risk of death, possibly because their fatty breasts may be a more favorable environment for tumor growth.

We do not know if additional breast cancer screening beyond mammograms saves lives.

Sonogram and/or MRI for breast cancer screening is currently not recommended based on breast density alone. Additional screening beyond mammography is only used in women at highest risk for breast cancer — those with cancer in a first degree relative with a high risk gene mutation, a family history suggesting one of these mutations, a Gail model or other combined lifetime breast cancer risk assessment >25% or a history of chest irradiation. Even in this group, declines in morality with the additional screening have not yet been shown, and the false positive rate of this additional testing is extremely high — only 20% of abnormals are cancer when biopsied.

There are no recommendations to use sonogram and MRI in otherwise low risk women, and none that have shown that using it based on breast density alone saves lives.

Additional screening beyond mammograms adds significant costs to breast cancer screening.

For some women, this additional cost may not be covered by insurance. While Connecticut has passed a law mandating that insurers cover additional sonograms, New York State has not.

What should you do if you’ve been told your breasts are dense on mammography? 

If you are at increased risk for breast cancer due to personal or family history, you may want to consider adding ultrasound or MRI screening.

Otherwise, at the point there is no recommendation that you do anything other than continue screening at whatever interval you and your doctor have decided is right for you. If having a sonogram will reassure you that you’ve done everything you can to screen for breast cancer, and are willing to accept the additional false positives and biopsies that may results from this additional screening, and understand that the additional screening has not been shown to decrease deaths from breast cancer in women at average risk, then ask your doctor to order you a breast sonogram.

Margaret Polaneczky is an obstetrician-gynecologist who blogs at The Blog That Ate Manhattan.

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  • Lisa

    As a breast cancer patient, who had dense breasts and multi-centric cancer that was not seen on a screening mammogram, I have mixed feelings on this topic.

    I think many of the laws that mandate women be told if they have dense breasts on a mammogram have been initiated by women who have been diagnosed with advanced breast cancer, after having regular mammograms. Given the ‘Komen’ propaganda, that early detection is equivalent to a cure and that every women should start having mammograms at 40, I think it is understandable that they feel outraged and want women to receive information about breast density, to have a chance to know what they think they should have known. But I also see a problem with the laws because they don’t provide for education on breast density and for that matter on breast cancer screening, beyond the broad statement that to talk to your doctor. I think most doctors do not adequately discuss the pros and cons of breast cancer screening with their patients. Furthermore, many ‘awareness’ organizations do not provide accurate information but just push mammograms.

    On the other hand, I wish I had remembered a mammogram report I received about eight years before my diagnosis. The report said I had extremely dense breast that were unsuited for mammograms and a negative finding on a mammogram was not a guarantee that I didn’t have breast cancer. If I had remembered that report when I was initially diagnosed with DCIS (discovered via mammogram) I would have pushed for an MRI before my initial surgery. That probably would have allowed me to have one surgery. As I was didn’t have an MRI until the radiation oncologist asked me to have one before beginning radiation. That led to another round of biopsies and a new diagnosis, in addition to further surgery. I was gob smacked when I discovered the report that mentioned my breast density when I picked up all of my reports and films from the breast center for my surgeon. Prophetic, I think….

  • Kristy Sokoloski

    In 1997/1998 I started having issues with my breasts, moreso my left one. The particular pain that I had also included some burning of the nerves around that same area. And it was because of that issue that I entered in to the world of breast cancer screening and such. That was the very first time I had a mammogram. I was 26. The results were normal. Finally, after a bit longer as the problem continued I went back to my Primary Care Physician at the time and took the film with me to her so she could see it. She was like “what’s that” when she saw the envelop on the counter by the chair where the patients sit when they are in the exam room. She was not a happy camper. In the mean time, I was on the pill due to some other female problems so I figured that the brand of birth control pill that I was on because the estrogen levels in them were too low that this caused the problem. She sent me for an ultrasound and the result was normal. But she was like “why on earth were you doing getting a mammogram” and I told her. Like I said she was not a happy camper. I also did some research on the issue by calling the breast center at one of the hospitals in my area. They too were surprised that the gyn I had at the time sent me for a mammogram because of my age: the fact that I was 26. And that’s when I learned as well that it is normal for a young woman’s breasts basically were supposed to be dense. Turned out that the problem that I thought was in my breasts was not actually in my breasts. It was with the cartilage around my ribcage. I was diagnosed with costochondritis (yep, another one of the problems that got added to a list of problems that I already have).

    In 2007, my relative was diagnosed with breast cancer. We are not sure what caused her to get it as far as a definitive cause. But I have a few possible causes in mind to consider. Once she got that diagnosis then I knew I better get a baseline screening mammogram. At the time I was 35. I had to have the hospital where I had the mammogram done taken to the imaging place so that they had something to compare with. Everything was ok up until the mammogram in 2010 where now a report came back saying that they wanted additional views and a sonogram. I refused for 3 years for 2 reasons, one more important than the other. They were: 1. I could not afford the cost of a diagnostic mammogram and ultrasound (and I am talking about the coinsurance and deductible that would have been applied to those procedures because the deductible had not been met yet for that year), and 2. I didn’t agree with the result of concern when the tech finally told me what that report said: I had an area of density. Ok, so I had an area of density big deal. Well, as I said I avoided it for 3 years. Last year when I went to my Primary Care Physician that I have now caring for me he asked me when my last mammogram was and I told him. And I told him the reason I had not followed up on the last one. He was going to be insistent that I do follow up but again I told him why I could not do it but he would not let this go. So I went. Well, when the hospital that I went to this time to get the mammogram done to do the necessary follow-up the tech told me that the radiologist looked at the report and said time to start from scratch. She explained that when these mammograms show something on them that require further testing that it is supposed to be done within 30 days. Otherwise, it’s no longer valid. No one had ever told me that before, but it still did not change the fact that I could not afford to have a diagnostic mammogram and ultrasound. I still can’t if and won’t ever be able to if I should ever get any kind of an abnormal finding on a mammogram or other screening test when it comes to diagnostic tests like that. And that’s even with the wonderful insurance I have that takes care of the biggest chunk of cost when it comes to payment. But the rest of the story on this issue is that then the radiology department had to call my Primary Care Physician’s office back to get a new order to get the regular screening mammogram done. That took about 45 minutes to do I think. And then they did the test which of course came back as I knew: normal. I told the tech that the range for what they considered to be a screening mammogram vs the actual diagnostic mammogram needs to be enlarged because the way it is now if a problem is found you have to come back for more views and more views. And when that happens you now run in to the diagnostic territory which then becomes money that she can’t afford to pay. But as it is, this year is the last time I will be having a well adult visit. Making the decision to cut this and the well woman visit out as I did last year was not the easiest decision for me but I knew it was the best for me in spite of what others may feel. As was mentioned in another blog entry I feel a lot of this also has to do with cultural aspect, but at the same time I can understand the position of others such as those that represent the Komen Foundation and similar organizations feel as they do. Same can be said for those that were diagnosed with breast cancer and feel like all the screening saved their lives.

  • PrimaryCareDoc

    This is what happens when we have legislators driving medical treatment. (Disclosure- I’m in my early 40s and I still haven’t gotten a mammogram).

    • Lisa

      Legislators with the special interest groups urging them to do so , , ,

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