Breast Density and Choosing Optimal Breast Screening

DenseBreast-info.org was set up in 2015 to provide ‏education to patients and healthcare providers about ‏dense breasts. How aware are women in the USA about ‏breast density? What still needs to be done?

As of 1 August 2016, at least 27 states in America require ‏some form of notification about breast density as part of the ‏mammography results letter to patients (densebreast-info.‏org/legislation.aspx). As such, more than half of American ‏women are receiving some information about breast density. ‏Breast density is described as one of four categories: a) ‏fatty; b) scattered fibroglandular tissue; c) heterogeneously ‏dense which could obscure detection of small masses; or d) ‏extremely dense which lowers the sensitivity of mammography. ‏The latter two categories are considered “dense”. About ‏40 percent of women of mammography age have dense ‏breasts, and dense breasts are normal.

Despite increasing requirements to inform women about ‏breast density, I think there remains a gap when women are ‏instructed to talk with their physicians about breast density ‏and what to do about it if they have dense breasts. I am very ‏proud to be part of the educational website DenseBreast-info.org, which launched i n April 2015 a s a collaboration ‏between myself, JoAnn Pushkin (patient advocate and ‏founder of DENSE-New York), and Cindy Henke-Sarmento ‏(technologist and entrepreneur). Our website provides much needed ‏information for both women and their healthcare ‏providers including defining breast density, discussing how ‏normal dense tissue can mask cancer detection on mammography ‏and that it is also a risk factor for developing breast ‏cancer. Most importantly, we discuss the potential benefits ‏and downsides to supplemental screening with ultrasound ‏or, when appropriate, MRI. We also present areas of ongoing ‏development in breast imaging such as contrast-enhanced ‏mammography and molecular breast imaging. Importantly, ‏breast cancer is often still hidden even on tomosynthesis (3D mammography).

What needs to be done in order to include all 50 states ‏in the dense breast notification policy? Are you aware ‏of similar policies overseas?

There is a need for a federal standard, either through a federal ‏law or preferably through regulation with an update to the ‏Mammography Quality Standards Act: (densebreast-info.‏org/is-there-a-federal-law.aspx). There are ongoing ‏discussions about informing women of their breast density ‏in several European countries. In Austria, for example, women ‏with dense breasts are routinely offered screening with ultrasound ‏as well as mammography (Graf 2014).

What role should MRI play in screening for women at high risk of breast cancer?

In 2007, based mostly on studies done in Europe, the ‏American Cancer Society issued guidelines for screening ‏high-risk women with MRI (Saslow et al. 2007), which have also been adopted in Europe. The challenge since then has ‏been how to identify such women, and how to make sure ‏those women who are at high risk for developing breast ‏cancer know about the option to have screening with MRI . Our ‏table: “Is My Mammogram Enough?” (densebreast-info.org/dense-breast-screening.aspx), is a good place to start, and ‏the flowchart “Who Needs More Screening” (densebreastinfo.‏org/who-needs-more-breast-screening.aspx) is also ‏very helpful. Even in normal-risk women, MRI allows detection ‏of more cancers than we see with the combination of ‏mammography and ultrasound. There are many barriers to ‏widespread use of MRI screening, however. MRI requires an ‏intravenous injection of contrast, and the examination is ‏performed with women lying on their stomach in a tunnel so ‏that women with claustrophobia may have trouble enduring a ‏breast MRI examination. Even when MRI is covered by insurance, ‏there can be a substantial copay or deductible in the ‏United States. I am glad that I knew enough about the risk ‏models and options to choose for myself to have a screening ‏MRI as my 3D mammogram (tomosynthesis) did not show ‏my own cancer. I have dense breasts, and ultrasound also ‏showed my cancer. Fortunately, while my cancer was invasive, ‏it was caught early, and I did not require chemotherapy. That ‏is the goal of screening. When screening works well, chemotherapy ‏can be mostly avoided. That said, like mammography, ‏ultrasound and MRI can result in the need for additional ‏testing such as a needle biopsy for findings that look ‏suspicious but turn out not to be cancer (false positives). I ‏hope that our website will provide women the information ‏they need to have educated discussions with their healthcare ‏providers to help them choose what is best for themselves, ‏given individual variation in tolerance for risks and benefits. ‏

Should MRI be used as an alternative for screening? Is ultrasound a reliable tool?

MRI is better at depicting breast cancer than the combination ‏of ultrasound and mammography across all breast ‏densities (densebreast-info.org/breast-imaging-technologies.aspx). MRI is also more expensive and not very ‏well tolerated by patients. Pioneered by Dr. Christiane Kuhl ‏and colleagues, there is the potential to use a shortened MRI ‏examination for screening to improve patient tolerance and ‏reduce costs (Kuhl et al. 2014). Several sites in the United ‏States are offering this and prospective multicentre evaluation ‏of this approach is planned. Ultrasound is widely available, ‏inexpensive, well-tolerated, and does not require any ‏injection. Unlike mammography, there is no ionising radiation ‏exposure from either ultrasound or MRI. While some cancers ‏can be found earlier on MRI, it appears that with the combination ‏of ultrasound and mammography, there is a very low rate ‏of “interval” cancers found because of symptoms before the ‏next recommended screening (Berg WA et al JAMA 2012). As ‏such, ultrasound remains an excellent option for most women ‏with dense breasts. For women at high risk because of known ‏or suspected disease-causing genetic mutations (such as ‏some mutations in BR CA1 or BR CA2), annual MRI is recommended ‏in addition to mammography beginning by age 30.

Women who had radiation therapy to the chest before age ‏30 and at least 8 years earlier (such as for Hodgkin’s disease) ‏are also recommended to have annual MRI. It is less clear at ‏what age to stop screening with MRI, but certainly it is not ‏cost effective beyond age 74. Our patient checklist (densebreast- ‏info.org/img/risk_checklist.pdf) can help prepare ‏a patient to discuss their risk factors and determine their ‏personalised optimal screening strategy with their physician.

‏You have raised the question of “Is having dense tissue ‏the cause of the risk, or just the amount of tissue density?” Please elaborate.

Not only can dense tissue mask cancer on mammography, but ‏dense tissue is also a risk factor for the development of breast ‏cancer. This is likely due to several factors, including the presence ‏of more glandular tissue where cancers develop and ‏also due to growth factors produced by the supporting tissue. ‏We also know that tamoxifen, a drug which blocks oestrogen ‏receptors, cuts in half the risk of developing breast cancer. ‏Several studies have shown that tamoxifen only produces that ‏benefit in women who experience a measurable decrease in ‏breast density while taking the drug. Most importantly, women ‏with dense breasts should be aware of any changes in their ‏breasts even if their mammogram is normal. Women need ‏to advocate for optimal screening so that breast cancer, if ‏present, can be caught early and easily treated.