Breast Cancer Screening Guidelines for Patients with Fibroglandular Densities
The Ohio legislature recently passed a law requiring that women who have screening mammograms be informed if they have dense breast tissue. Specifically, women who have dense breast tissue will receive the following statement in writing as part of their mammogram result: “Your mammogram demonstrates that you have dense breast tissue, which could hide abnormalities. Dense breast tissue, in and of itself, is a relatively common condition. Therefore, this information is not provided to cause undue concern; rather, it is to raise awareness and promote discussion with your health care provider regarding the presence of dense breast tissue in addition to other risk factors.”
For years, radiologists have routinely reported breast density as part of their interpretation, which is in the report sent to the patient’s physician or available on an electronic medical database. However, up until now it has not been a part of the standard letter that women receive when their mammogram is negative.
Take Home Points for Clinicians
- Ohio law requires that patients be informed if they have dense breast tissue on screening mammography, and if so, that they may want to discuss their screening options with their primary care physician.
- Approximately 50 percent of women undergoing screening mammography are classified as having either heterogeneously dense or extremely dense breasts. For all of these women, the patient letter will inform them that they have “dense breast tissue.”
- Only 10 percent of all women have extremely dense breast tissue, which is associated with a relative risk of breast cancer of approximately 2.0 compared with average breast density. Forty percent of women have heterogeneously dense breast tissue, which is associated with a relative risk of approximately 1.2. Therefore, breast density is not a major cancer risk factor.
- The sensitivity of mammography is reduced as background breast tissue density increases. When mammography is the only screening test performed, sensitivity decreases by 10 to 20 percent for women with dense breasts.
- The recommendations for screening mammography are exactly the same for women with dense breasts as for the rest of the population. Mammography is the only screening modality that has undergone randomized controlled trials demonstrating a reduction in breast cancer mortality. There is no recommendation that it be replaced with another test in any subset of the population.
- For patients who are interested in additional screening options, a breast cancer risk assessment may be appropriate. It is a good starting point in the discussion of whether supplemental tests will be beneficial and what tests, if any, to order.
- The other breast imaging screening options include screening magnetic resonance imaging (MRI), ultrasound and 3-D mammography (tomosynthesis). Screening breast MRI has been shown to substantially increase the rate of cancer detection. It is recommended in patients who are at very high risk (greater than 20 percent lifetime risk), based on American Cancer Society guidelines. For patients at intermediate risk, such as those with a personal history of breast cancer or a prior biopsy diagnosis of atypia (equivalent to a 15 to 20 percent lifetime risk), a patient-centered shared decision-making approach is recommended.
- Screening breast ultrasound is offered at University Hospitals Minoff Health Center at Chagrin Highlands, UH Breen Women's Health Pavilion at University Hospitals Cleveland Medical Center, and St. John Medical Center. Small studies have shown a modest increase in cancer detection, but also a high rate of false positives resulting in benign biopsies. The choice to have this test should be made on an individual basis after a discussion of these risks, benefits and costs.
- Breast tomosynthesis (3-D mammography) is being offered in addition to screening mammography at multiple sites in the UH system. There is encouraging data on the performance of tomosynthesis in women with dense breast tissue. Tomosynthesis increases cancer detection and reduced false positives and unnecessary biopsies.