A recently published study concluded that having dense breasts “eclipse all other known breast cancer risk factors” (Ref. 1). Sixty percent of women under the age of 50 have dense breasts. Thus, more than half of all young women are unaware of their increased risk of developing breast cancer.
Having dense breasts is not only a major risk for developing breast cancer but makes it more difficult to detect small cancers on mammography (Ref. 2-3). Also, breast cancers that are detected in young women tend to be more aggressive and faster growing than are breast cancers detected in women with fatty breasts (Ref. 4). A recent study concluded that women under the age of 40 had twice the risk of dying from breast cancer than women aged 51 to age 60. Of note, the study was performed in women with estrogen and progesterone receptor positive tumors (Ref. 5).
The only way to determine breast density is with a mammogram. Although many women assume their breasts are dense because they feel lumpy, neither the patient nor her doctor can determine density status based on physical examination alone.
Dense breast tissue is composed of a combination of glandular and fibrous supportive tissue which appears white on the mammogram. If more than half of the mammogram is composed of this white tissue, it is classified as being dense. The challenge of detecting a small cancer in women with dense breasts is that both the cancer and the background are white. Detecting a small cancer in a dense breast has been compared to trying to find a snowman in a snowstorm.
Fatty breast tissue is black on the mammogram. The black background makes it easier to detect small white cancers on screening as noted in the following images. Image 1 is an example of a small cancer in a fatty breast. Image 2 is an example of a dense breast. In comparing the two images, it is easy to imagine how the small cancer in image 1 would be difficult to detect on image 2.
Despite the benefits of mammographic imaging, challenges remain. It is estimated that 1 in 8 women who have a screening mammogram will have a breast cancer that is not detected on the mammogram. Failure to detect a “hidden breast cancer” is referred to as a false negative mammogram (Ref. 6).
Progress has been made in reducing the risk of a false negative mammogram. New technology referred to as the 3D mammogram or tomosynthesis is effective in detection of small breast cancers missed on the older 2D technology. A recent report concluded that 3D mammograms reduce the rate of a false negative by 40% (Ref. 7). We recommend that a woman’s first mammogram be performed using 3D technology. If the breast is found to be dense, yearly screening with a 3D mammogram is recommended (internal link to our screening guidelines).
As a result of the multiple challenges in diagnosing early-stage breast cancers in women with dense breasts, it has recently been suggested that all women should consider the option to start mammographic screening in their 30s (Ref. 8). We agree with this recommendation and advise women to be given the option to have their first (baseline) mammogram at age 35 (link to our guidelines). If the baseline mammogram concludes that the breasts are dense, we recommend that women with dense breasts should continue yearly screening with 3D mammograms if healthy.
An additional early detection technology is to add screening ultrasound to the screening process. We recommend that women with no family history of breast cancer have a screening breast ultrasound in addition to the 3D mammogram. It has been reported that adding the screening ultrasound is associated with a 24% increase in detection rates of breast cancers (Ref. 9).
The second option is the screening MRI which is the most accurate test available to detect early breast cancers (Ref. 10). Because of its cost, the screening MRI is reserved for women at high-risk. For example, we advise women with a family history of breast cancer to obtain a risk assessment consultation. If a woman has a lifetime risk of 20% or greater of developing a breast cancer the insurance company will often pay at least part of the cost of a screening MRI.
A new early detection technology is on the horizon. Artificial Intelligence (AI) is now being integrated into the process of digital mammography (see internal link and Ref. 11-12). Early studies indicate that AI has the potential to be a game changer in the early detection of “hidden” breast cancers missed on screening mammograms. AI can also lower the risk of having a biopsy that proves not to be cancer (false positive).
We realize that for many women, the cost of more aggressive screening will be a major concern. However, to put the issue of cost into perspective, the out-of- pocket expense of aggressive screening is approximately the same as it would be to purchase a daily cup of coffee from Starbucks over a one-year period.
- Dense Breasts’ Eclipse All Other Known Breast Cancer Risk Factors
- Dense Breasts: Answers to Commonly Asked Questions
- Dense breast tissue: What it means to have dense breasts
- Women With Dense Breasts Have Higher Risk of More Aggressive Cancer
- Do Young Women Have Worse Breast Cancer Outcomes? It Seems to Depend on the Cancer’s Characteristics
- Limitations of Mammograms
- 3D Mammography More Likely to Find Small Invasive Breast Cancers, Especially in Women Younger Than 50
- Study: Some Women Should Start Mammograms at 30
- Screening breast ultrasound: past, present, and future
- Breast MRI
- RadNet touts AI offshoot’s early success, pinpointing cancer a year earlier than current practice
- Rad/Net Bringing AI to Imaging Centers
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