What You Need to Know About the Breast Density Law

dense breastessentially fattyCan you identify which image here is the dense breast? If you guessed the one on the left, you’re right. Were you aware that this year Massachusetts implemented a law that requires all mammography providers to notify patients in writing of their breast density and why? Read on to learn what you need to know about this new law.

Radiologists have routinely reported breast density, but until this year it had not been part of the standard letter that patients received after a mammogram. The Massachusetts breast density law that went into effect this past January requires all mammography providers to notify patients in writing of their breast density. In addition and in the same letter, approximately 50 percent of women who have a screening mammogram will be informed to consider additional breast cancer screening options because they have dense breasts.

There are four different levels of breast density as defined by the American College of Radiology:

  • Almost entirely fatty or essentially fatty: Most of the tissue is made up of fat cells
  • Scattered areas of fibroglandular density: Some tissue is fatty and some is either fibrous or glandular
  • Heterogeneously dense: More than half the tissue is fibrous or glandular
  • Extremely dense: Most of the tissue is fibrous or glandular

The size of a woman’s breast is not indicative of density levels. For example, one woman may have small but extremely dense breasts, while another woman might have large but very fatty or non-dense breasts. About half of all women have either heterogeneously dense or extremely dense breasts.

Twice as Likely to Develop Breast Cancer

According to Dr. Gopal Vijayaraghavan, our director of breast imaging, women with extremely dense breast are twice as likely to develop breast cancer as women with average density breasts (as determined by the California Breast Density Information Group). The risk associated with extremely dense breasts is similar to the risk associated with a family history of breast cancer in a mother, sister or daughter.

Breast density itself is not a major cancer risk factor. However, having dense breast tissue makes it harder to find breast cancer on a mammogram. The fibrous or glandular tissue in dense breast can “mask” an underlying abnormality.

What Breast Cancer Screening Tools Are Available?

Mammography is estimated to be only 48 percent effective in dense breasts, compared to 98 percent effective in fatty breasts (DMIST Trial). Therefore women with dense breast may be risk stratified and told they may benefit from additional imaging if indicated. In addition to the traditional mammogram, breast cancer screening tools include:

  • Screening breast MRI
  • Screening breast ultrasound
  • 3D Tomosynthesis (sometimes called 3D mammography)

Each of the screening tools carries benefits and risks. Breast MRI has demonstrated to be a useful screening tool in patients with a very high risk for breast cancer. However, both MRI and ultrasound are associated with a much higher rate of benign biopsies. The 3D mammography carries with it higher doses of radiation exposure.

Dr. Vijayaraghavan said that patients who have dense breast should continue to get mammograms. While mammogram sensitivity is somewhat lower in women with extremely dense breast, it’s still a crucial screening tool. He noted that mammography remains the only test that identifies suspicious calcifications, the first sign of in-situ cancers, which comprise about 20 percent of all breast cancer cases.

In addition, a patient should speak with her health care provider about possible next steps. Dr. Vijayaraghavan said that there are several factors which influence a patient’s risk level, including age and family history. These risk factors can help determine whether supplemental screening is appropriate, and if so what is the best way to proceed.

Join the conversation. Do you talk to your doctor about breast cancer risks? Do you get regular screenings?

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