Breast Density: An independent risk factor for developing breast cancer

Image of a group of women.

Through the efforts of patient advocacy groups and breast imaging professionals, breast density has become a hot topic over the last several years. There has been a nationwide campaign at the state government level to require centers that provide mammogram services to notify patients if their breast tissue is dense and to encourage the patient to seek further discussions with their health care provider. Legislation has passed in over half of the U.S. states thus far including Florida, which passed in July 2018. At a national level, the Food and Drug Administration (FDA) recently drafted changes to the 1992 Mammography Quality Standards Act (MQSA) in order to: improve patient understanding of the relationship between breast density and breast cancer risk, provide physicians with more detailed information to improve mammogram assessments, and provide the FDA with the ability to better enforce the MQSA regulations

Dense breasts are most commonly found in the 40-50 age group, with 40-50% of women aged 40-74 having this pattern. Breast tissue composition is unique to an individual and is partially inherited. There are other non-inherited factors that influence breast density such as body mass index and exogenous hormones. Dense breast tissue is a mix between fibroglandular tissue and fat. Because the density of breasts cannot be determined by a physical exam, mammograms are the best way to assess the density of a patient's breast tissue. In the past this was assessed subjectively by the interpreting radiologist. There are four categories for breast density: predominately fatty, scattered densities, heterogeneous densities, and extremely dense. "Dense breastsapplies to the last two categories

Why is it important to inform patients and referring clinicians about breast density? Breast density is an independent risk factor for developing breast cancer. Besides increasing age and female sex, dense breast tissue is the most prevalent common risk factor for breast cancer. There is a two-fold increase in developing breast cancer in women with heterogeneously dense tissue and a four-fold increase in women with extremely dense tissue versus women who have predominantly fatty or scattered breast tissue. Dense breast tissue is thought to cause this increase for at least two reasons. Firstly, the percent of active glandular tissue is greater so there are more dividing cells thus more chance for cancerous mutations. Secondly, the tissue around the glands may produce growth hormones that stimulate cells to divide

Not only does dense breast tissue increase one's risk for developing breast cancer, it can mask a cancer on mammogram, making detection harder. Fifty percent of breast cancers can be missed on 2D mammogram with dense breast tissue. Slight improvement in detection has been seen with the addition of 3D mammogram (tomosynthesis). Detection can be further improved with the addition of supplemental screening studies such as ultrasound or Fast MRI. Adding ultrasound to a 2D/3D mammogram increases the detection rate by 3-4 cancers/1000 women. Adding Fast MRI to a 2D/3D mammogram increases the detection rate by approximately 10 cancers/1000 women. Ultrasound is more widely available, less costly and does not require contrast administration; however, Fast MRI IS more sensitive and specific than ultrasound. Please be aware that in Florida, health insurance payors do not consider breast ultrasound and Fast MRI as screening tests, and therefore they do not apply as preventative services

Increasing awareness through lay letter notification legislation will hopefully encourage patients to discuss their particular breast cancer risks with their health care providers, and develop a breast cancer screening plan that best suits their individual needs

The TopLine MD imaging centers' fellowship-trained breast radiologists are here to support you in caring for your patients' breast health. We have instituted the following procedures to assist our patients and referring physicians with breast density concerns and management

Dr. Carrie JW Horst, DO is Medical Director / Clinical Director of Ancillary Imaging Services at TopLine MD Health Alliance. Do you have a question for Dr. Horst? Please send questions to chorst@femwell.com

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