THE BLOG
10/01/2014 11:56 am ET Updated Dec 06, 2017

Breast Density: How to See Clearly Through the Fog

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It's Breast Cancer Awareness month, but unfortunately for me, I've been all too aware of breast cancer since my own diagnosis in January of 2013.

My story is no different than the ones you've heard: A 40-year-old woman in great shape and good health suddenly notices a dime-size puckering in her left breast. I called Dr. Kristi Funk's office immediately. A biopsy confirmed my cancer, and suddenly I was off to the races with no idea of what just happened.

I was very conscientious about yearly check-ups. Because my breasts were diagnosed as dense tissue, I had been receiving regular ultrasound screenings at Pink Lotus Breast Center. Dense tissue makes it harder to evaluate a mammogram.

For years, radiologists have commented about breast density as part of their report, which is sent to a patient's physician. However, it has recently become mandatory in 19 states that density reporting be included in the standard letter that women receive when their mammogram is negative.

The California legislature passed a law requiring that women who have screening mammograms be informed if they have dense breast tissue. This information is given to raise your awareness and to discuss with your doctor. Together, you can decide which additional screening options are right for you including ultrasound, MRI, contrast enhanced mammograms and tomosynthesis.

Why is this important? Well, after the dimpling was diagnosed as a cancerous mass in my left breast, Dr. Funk sent me to have an MRI. An MRI is a very useful tool in screening dense breast tissue. It can read abnormalities that an ultrasound and mammogram can't detect due to dense tissue and cancer both presenting white on film. The two then hide one another, and cancer becomes harder to discern.

My MRI showed a suspicious lesion in my right breast, which was clearly overlooked by my ultrasound. We were all taken aback.

The MRI revealed the early stages of an aggressive type of breast cancer, HER2 positive, which could have quickly gotten out of hand had it not been detected.

Needless to say, I chose to have a double mastectomy and reconstruction while going through treatment.

I sat down my breast cancer surgeon, Dr. Kristi Funk of Pink Lotus Breast Center, to discuss and understand breast density and how it impacts women's screening options.

Q: Dr. Funk, can you explain what breast density is?

A: Breast density is a visual comparison on mammogram between actual breast tissue, which is white, and fat, which is grey/black. The whiter the mammogram, the denser the breast.

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All women with density levels 3 and 4 (heterogeneously dense and extremely dense) will be informed that they have dense breasts under the new density laws. Most women fall into the middle two groups, with the distribution as follows: 10 percent level 1, 40 percent level 2, 40 percent level 3, 10 percent level 4. (American College of Radiology)

Q: So, about 50 percent of women have dense breasts. Why does that matter?

A: Breast density is like mammogram's dirty little secret. Half of women over 40 have no idea that their "normal" mammogram might not be normal at all. We are looking for a snowball in a snowstorm! You see, cancer is white, and dense tissue is white. So, dense breast tissue can overlap with cancers, masking them from view; in fact, we miss up to 50 percent of cancers in dense breasts. (Kolb, et al.) Secondly, dense tissue is the part of the breast that gets cancer, not fat, so there is a higher risk of getting cancer for women with dense breasts. Density level 4 women have five times the cancer risk as a density level 1. (NEJM)

Q: How is breast density determined?

A: Most centers rely solely upon radiologists to make a subjective visual assessment of density. We at the Sheryl Crow Imaging Center in the Pink Lotus Breast Center were the first in Los Angeles to use an objective, computerized assessment of breast density, developed by GE, called Volpara. Volpara provides our mammographers with a standardized and reproducible density assessment, which they use as a "second opinion" on the density rating.

Q: Dr. Funk, should patients who receive a letter confirming dense breast tissue continue to get routine mammograms?

A: Yes, yes, yes! Mammography is the gold standard in screening because it's the only tool that has been repeatedly proven through countless studies to decrease death from breast cancer. Those trials included all breast densities. Mammograms are fast, cheap, widely available and plenty of radiologists can read them -- while clearly not a perfect test (especially with dense tissue), mammograms find cancer and absolutely save lives. Also, mammography is best way to find suspicious calcifications, which are often the only sign of an in situ cancer. In situ cancers coexist with invisible invasive cancers 20 percent of the time. (Hoorntje et al.). [1]

Q: Can you talk about additional screening options available?

A: Screening breast MRI and screening breast ultrasound (SUS) have been studied the most. Both tests look at tissue differently than a mammogram and are less impacted by density. As such, both MRI and SUS increase cancer detection over mammography alone, MRI much more so than ultrasound. Now the bad news -- both MRI and SUS lead us down what I call "the rabbit hole" -- unclear findings that cause benign biopsies and/or recommendations for short term follow-up, which, in turn, create more anxiety and higher costs. At our center, we individualize the risk/benefit ratio and find that women with dense breasts plus additional breast cancer risk factors ultimately benefit the most from additional testing. (Berg et al.).

Two newcomers to the imaging scene include Contrast Enhanced Spectral Mammography (sometimes referred to as "CESM" or "SenoBright") and breast tomosynthesis (also called "3D mammography"). These exist in some radiology practices, but their use has not been as completely studied as either MRI or ultrasound. Early data suggest that CESM rivals MRI in cancer detection (Fallenberg et al.), and tomosynthesis may increase findings to about the same degree as adding ultrasound. Importantly, both exams may decrease rather than increase the rate of false positives. We await more robust evidence on the benefits and limitations of both CESM and tomosynthesis.

Q: So if a woman has dense breasts, a risk assessment may be helpful to determine further choices of screening?

A: Definitely. In addition to density, a number of important risk factors may come into play, and knowing a specific patient's risk level helps determine whether supplemental screening is appropriate.

Q: What would you determine as high risk?

A: The strongest risk factors for breast cancer, other than advancing age and being female, are personal or family history (especially a first degree relative with premenopausal breast or ovarian cancer) and personal history of atypia on prior biopsy (cancer.gov). We always refer women suspected to be at high risk to our genetics counselor for risk assessment and genetic testing, when appropriate. When the lifetime chance of breast cancer exceeds 20 percent, we always recommend more than a mammogram for annual surveillance.

Q: I have to ask: What will the cost of supplemental screening tests be to patients and to the health care system?

A: Well, now, that's a problem. By California law, women need to be told they are at higher risk with dense breasts, but the law did not mandate insurance coverage for any extra screening tests. Also, billing codes do not exist for screening breast ultrasound, CESM, or tomosynthesis in California, so there is no legal way to bill insurance for these services. Luckily, MRI is usually covered for high-risk women, but that does not include the average risk woman with dense breasts as her sole issue. So, women who desire certain types of supplemental screening may be asked to pay out of pocket.

Q: It was always peace of mind to have the additional screening. Clearly in my case, the MRI picked up a second cancer in the opposite breast. I can't thank you enough for saving my life, let alone the countless number of other women you're saving every day. You're my hero.

A: Ah, Nikki, I'm grateful for your gratitude -- which inspires me to do my best every day. Our deepest hope is to save lives with the screening and services that Pink Lotus provides. We look forward to creating new Pink Lotus Breast Center locations throughout Southern California, starting with Santa Monica this month!

Reference:

[1] Lidewij E. Hoorntje, MD, et al. "The finding of invasive cancer after a preoperative diagnosis of ductal carcinoma-in-situ: causes of ductal carcinoma-in-situ underestimates with stereotactic 14-gauge needle biopsy." Annals of Surgical Oncology, 10(7):748-753