August 7, 2012 Celeste Monforton, DrPH, MPH 19Comment

I feel dense for not knowing this important public health fact: women with extremely dense breast tissue are at least four times more likely to develop breast cancer.

Over the years, I’ve had my routine screening mammograms with stellar results.  No evidence of cancer in my two mammary glands.  I’ve heard radiology technicians comment about my dense breasts, but I thought it was an interesting attribute like droopy breast, or perky breasts or double D breasts.

In December 2011, just before my 50th birthday, I was overdue for my routine screening mammogram.  I felt a little guilty for putting it off, but the results were the same as always:

“Bilateral mammography shows extremely dense breasts throughout which are scattered with occasional benign microcalcifications bilaterally.  Breast pathology is not suggested.  Recommendation: Annual screening mammography.”

Just like always, my mammogram results showed nothing to worry about.  Pencil on the calendar my next mammogram in 12 months.

Fast forward five months.  My left nipple starts looking sorta like this and I made an appointment with my local nurse practitioner.  A few diagnostic tests later and here’s the diagnosis: Stage IIIB invasive ductal carcinoma.   In plain English, I have a 7 cm tumor in my breast that’s already spread to my lymph nodes.

“Seriously?  7 cm? What about that mammogram I had just a few months ago?” I ask myself and the physicians.  “Mammograms are like reading the clouds,” one radiologist responded.   “And you have really dense breast tissue,” he added.

Breast tissue density is a mammographic indicator of the amount of glandular tissue in the breast relative to fatty tissue.  There are two qualitative classification systems to characterize it, the Wolfe grade and the American College of Radiology’s BI-RADS.  What I didn’t know—-and feel ignorant for not knowing—-is high breast tissue density is a strong independent risk factor for developing breast cancer.  Epidemiological studies consistently find a 4- to 6-fold increased risk of breast cancer for women with high breast density compared to those with less dense breasts (e.g., here, here, here.)  Epidemiologists Valerie McCormack, PhD, MSc and Isabel dos Santos Silva, MD MSc PhD of the London School of Hygiene & Tropical Medicine conducted a systematic review and meta-analysis of 15 studies that used quantitative methods to assess mammographic density and breast cancer risk. In their 2006 paper published in Cancer Epidemiology, Biomarkers and Prevention they reported:

“The combined data presented here confirm that breast density, measured using either Wolfe grade or percentage density, is strongly associated with breast cancer risk, as determined by general population studies of either incident or prevalent cancer risk.”

I created the following table using McCormack and dos Santos Silva’s calculations of combined pooled relative risks (RRs) for breast tissue density categories.

My December 2011 written mammogram result merely said “extremely dense breasts.”  I know now that meant my breasts reside in the >74% category.  Based on McCormack and dos Santos Silva’s analysis, on the breast-density factor alone, women like me have an increased risk of breast cancer that is 3.64 to 5.91 times higher than women in the <5% breast density category.

The authors also qualify their statement with the following:

“the true association may be even stronger, as non-differential measurement error of breast density would lead to underestimation of associations. Assuming moderate error (intraclass correlation of 0.90), RR estimates for categories 50% to 74% and ≥75%, when corrected, would increase to 3.29 and 5.50, respectively.”

The more I started looking at the scientific literature, the more I found, and the more dense I felt.  Writing in 2008 in the British Journal of Cancer, researchers with the Ontario Cancer Institute in Toronto wrote:

“…Extensive breast density is therefore one of the strongest known risk factors for developing breast cancer, second only to age and carrying a BRCA1 or BRCA2 mutation.  Although less than 5% of unselected breast cancer patients have a BRCA1 or BRCA2 mutation, extensive mammographic density is common among women with breast cancer, and estimates of attributable risk show that densities in more than 50% of the breast may account for about a third of all breast cancers.”

On a mammogram, fatty breast tissue is radiolucent and appears black, while connective tissue absorbs x-rays and appears white.  It is this denser tissue comprised of collagen, stromal tissue and epithelium cells that are correlated with breast density and make abnormalities more difficult to distinguish on mammograms.  But the increased risk is not simply a failure of the human eye reading mammograms.  Researchers have several hypotheses on potential biological mechanisms to link mammographic density and breast cancer risk.

For all these years, I’ve known some of the highest risk factors for the disease, such as being over age 65 years, inheriting the BRCA1 and/or BRCA2 genetic mutation, receiving high-dose radiation to the chest, and having two first-degree relatives (i.e., mother, sisters) with breast cancer (see page 12, Figure 4 in ACS Breast Cancer Facts & Figures, 2011.)    But breast density, how’d I miss that one?

Now I’ve learned I’m not the only one.  The  Density Education National Survivors’ Effort (D.E.N.S.E.) are other women like me who:

“…received–year after year—the  one sentence lay report either stating ‘No evidence of cancer’ or  ‘Results of your recent mammography examination are normal/benign (not cancer.)'”   The group says:  “… A letter indicating ‘no cancer’  is clearly an inaccurate representation of reality if a radiologist knows that, due to density, there is a significant chance a tumor could be missed.  If a ‘summary’ of  a mammography report doesn’t include any mention of breast density, its inherent risk, and the possible limitations of a mammogram in finding a tumor because of density, then one has to wonder what its purpose is at all.  …When women aren’t told about their own breast density and its inherent risk, they are denied the opportunity to protect and advocate for themselves.”

D.E.N.S.E. and other health-promotion groups worked with lawmakers in the Connecticut to pass a law in 2009 requiring radiologists to inform woman receiving mammograms about their breast density.  The law includes the following provision:

“… each mammography report provided to a patient shall include information about breast density, based on the BI-RADS by the American College of Radiology. Where applicable, such report shall include the following notice: ‘If your mammogram demonstrates that you have dense breast tissue, which could hide small abnormalities, you might benefit from supplementary screening tests, which can include a breast ultrasound screening or a breast MRI examination, or both, depending on your individual risk factors. A report of your mammography results, which contains information about your breast density, has been sent to your physician’s office and you should contact your physician if you have any questions or concerns about this report.'”

Similar laws have been passed in Texas (effective date May 1, 2012), Virginia (effective date July 1, 2012),  and New York (effective date January 2013), with varying degrees of specificity in the text of the required notice.  Some organizations representing radiologists have argued that women would be alarmed unnecessarily by the notice.  In some cases, they’ve succeeded in getting it toned down.  At the federal level, Rosa deLauro (D-CT) and Steve Israel (D-NY) introduced the Breast Density and Mammography Reporting Act of 2011 (H.R. 3102) which would require radiologists performing mammogram to report breast density findings to physicians and patients.

I’ve been keeping friends and colleague apprised via CaringBridge on the initial phases of my treatment.  I’ve happily heard from a few who’ve said “I’m one of those dense-breasted woman, too.”  I responded to a few with this about my December 2011 mammogram:

“Hello! why don’t they put at least an asterisk after ‘extremely dense breast tissue’ that says ‘you are at higher risk of breast cancer’?  Better yet, why aren’t ultrasounds part of the standard screening protocol for women with dense breasts?   The mammogram that couldn’t distinguish my 7 cm tumor or the smaller tumors around it, gave me a ridiculous false sense of health.”

Now I know there are individuals across the country trying to get laws passed to do exactly that.  How could I be so dense?



19 thoughts on “Dense breasts are not just an interesting attribute, wish I’d known the cancer risk

  1. Thank you very much for your willingness to share your own experience, and best of luck to you in your treatment. There are also suggestions that women who have large breasts are at higher risk (this may be the source of the observation that women who wear bras round-the-clock are at higher risk). Since cancer usually arises in the glandular tissue, it seems very plausible that the more glands a woman has, the more potential for cancer. I have dense enough breasts that mammography doesn’t really show anything (and I decided routine screening is not a good deal at my current age anyway, given my total lack of family history), but I also have dinky little breasts. Do you happen to know if there’s any way of finding out whether one actually has an abnormally large amount of glandular tissue, or just a normal volume of glands but an unusually small amount of fat surrounding them? It seems to me that a dense A-cup and a dense D-cup must be two different things, riskwise.

  2. Jane,
    I’m a newbie at this, but based on my preliminary look at the literature, both the Wolfe grading and BI-RADS classifications for breast density will give you some insight on the amount of glandular tissue in your breasts relative to fatty tissue. (Each of these grading systems have four categories from low breast density to high density.) This piece of information is what the group D.E.N.S.E. and others are urging be disclosed on mammogram results.

    With respect to your comment about A-cup versus D-cup bra-wearers, I did not see anything in the scientific literature suggesting that breast size alone is a risk factor for breast cancer. Based on what I’ve read, dense breast tissue can be a feature of both small breasted and large breasted women.

  3. There’s some evidence for it – on PubMed, I find Kusano et al., A prospective study of breast size and premenopausal breast cancer incidence, Int. J. Cancer 2006;118:2031-4. For women of normal weight, the adjusted hazard ratio was 1.8 for a D cup vs. an A cup. Of course, that exaggerates the risk increase from being a D cup, relative to the average woman, in much the same way that McCormack and dos Santos Silva’s numbers do for the risk from having dense breasts. The average normal woman isn’t an A cup and, as your footnote implies, doesn’t have a breast density <5%. The B or B+ cups, being in the middle of the bell curve, ought to have been assigned the 1.00 relative risk, with a risk below 1.0 on the left and above it on the right; the increased hazard ratio associated with being a D cup would then look much less scary. Still, since the average D cup surely has more glandular tissue than the average A cup, their results are entirely compatible with the breast-density hypothesis.

  4. Sorry to hear about your diagnosis, I really enjoy your posts and learn a lot from them. I will hope for a speedy recovery.

  5. I also have been attentive to the risk factors – I thought – an having none have mammograms about every 3-4 years. But until this year I had ultrasound as well because of my dense tissue (% never mentioned). But at my last mammogram i was told insurance would no longer cover it. As your information suggests this is not a routine but a needed procedure, I am going to find out how to get it covered, and share that information when I have it. Thanks for the heads up, Celeste.

  6. Celeste – My sincerest wishes for a complete recovery. And you are doing a real service by bringing light to this issue.

  7. Celeste, me and my husband, Scott, (yes this is the one you know) wish you a complete recovery and our prayers are with you.. I have also had a scare with breast health.. two years in a row I have had to have biopsy after biopsy but all have come back clear.. I go every 6 months for mammograms watching spots.. I am only 47.. Thank you for this article. I will pass it on..

  8. So sorry to hear about your diagnosis, Celeste. Best wishes on your treatment and for a full recovery. I also have extremely dense breasts and (having worked on breast cancer epidemiology for my dissertation) WAS aware that this placed me at higher risk. I essentially gave up on mammography a couple years ago (I’m in my mid-40s now), because it is so useless at seeing anything in the snow-cloud that is my breast image. I’ve been fighting with my insurance company to pay for MRI for screening, but they won’t because they require use of a specific breast cancer risk calculator, which does not take into account breast density. Perhaps these breast cancer risk calculators need to be updated to include information on breast density, one of the most common risk factors for breast cancer.

  9. Celeste, best wishes for a quick and complete recovery and thanks so much for sharing this valuable information. I’m due for my annual exam shortly and will make sure to find out if I fall into this category, as I cannot recall any info on density on any prior mammo reports. This is important information to share!

  10. Celeste,
    What tough news. I’m amazed at and thankful for your fortitude in putting this blog post together in the midst of what you’re dealing with. You’re in my thoughts and I’m sending positive, healing vibes your way. Kathy

  11. Celeste, I send positive thoughts and strength for the future. I’m 43 and have been having mammograms from age 30 due to family history. Like you I had a clear result in Jan 12, in May I noticed skin dimpling. Focused ultrasound and biopsy identified 1.5cm IDC. I’ve just had a mastectomy and as well as that tumour there was a further 2.5cm DCIS and some early stage LCIS. Density of my breasts was mentioned once when I was in my 30’s but I’m not a Dr and didn’t understand the significance. I agree this is something women really need to be told about and followed up on more proactively.

  12. Cinnabar,
    Wishing you the best of health in the years ahead. I was hoping to hear that breast screening protocols in the UK are more advanced than in the USA. We need to find out if any countries do it better.

  13. Sending good wishes your way. THANK YOU for this article. Ive been wondering for a decade why Kaiser doesnt have ultrasound screenings. Your article will educate a lot of people. I plan to share it with my doctors.

  14. I have dense breasts. Stage 2 ductal carcinoma removed 2/1/2011 – I found it by accident – it never showed up on mammograms even when it was 1 cm and we knew it was there – mammogram didn’t see it. The first MRI on 1/11/2011 showed a 2nd lesion where I have been having all this pain and first they said it was mondors disease, then they said it’s CRPS but the Pain center they sent me to disagrees and never heard of CRPS in the breast so I’m in limbo and there is a lump in my breast and I feel like a problem patient. My first surgeon retired 6/30/2011, my replacement breast specialist is leaving her practice to join another breast center but she hasn’t helped me anyway. I had a 2nd opinion. Ever since my surgery I’ve had pain where the 2nd lesion with worrisome kinetics was located 1/11/2011. My 3rd breast surgeon talks down to me like I’m stupid. But nobody can explain what happened to the 2nd lesion. I didn’t have to have chemo. I had 35 treatments of radiation and I’m on Aromasin. Pain when I’m bumped. Can’t hold babies.

  15. Thanks Celeste for the information you are sharing. I contacted you on Facebook to see if you would be interested in aiding me with some information for a case study for my nursing class. Please let me know if you are able to do this. Thanks.

  16. thanks for sharing this and best wishes to you. i am 42 and just had my first mammogram. my ob/gyn suggested an mri when she saw how dense my breasts were. when they tried to schedule, they were told i’d have to pay for it 100%. i’m new to this. i had no idea a dr. could recommend treatment that the ins. co. (providence) would deny. then i went to a breast specialist/oncologist. she also recommended mri. it was denied. she recommended bsgi. it was denied. i asked about ultrasound, the oncologist said i could do it if i want but it’s not as effective as mri or bsgi. she reminded me i’m not high risk and is recommending another mammogram next year or another opinon. i don’t need a 3rd dr. telling me i should get an mri just to have it denied! feeling just overwhelmed, scared and furious. seems like drs. won’t walk through this with me once the mri is denied. so unclear as to what to do with this info. and just exhausted dealing w/ drs., their staff and ins. companies. i’m working on my appeal to the ins. co, but don’t have any hope it will be successful.

  17. I recently had my 2nd mammogram (I am 41), first one came back as “normal”. I received a phone call from my doctor’s office referring me to an imaging center because I have dense breast tissue. Although I have an appointment on Monday, I am blown away by the results. I didn’t get the same results a year ago. Could my density have changed? Maybe the protocols are changing because of people like you and the research that is coming to light! Thank you for posting your story, it has given me information to ask about and take control of my health!

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