Dense Breast Tissue
What is breast density?
Each woman’s breasts are unique and have varying amounts of fat and breast tissue. Breast density is measured as the total percentage of tissue in the breast:
- High breast density means there is more breast tissue compared to fat
- Low breast density means there is more fat compared to breast tissue
Having high breast density is perfectly normal. Breast density affects what your breasts look like on a mammogram. Dense breast tissue has the potential to hide cancer on a mammogram and is a risk factor that may increase a woman’s chance of developing breast cancer by 4-6 times as compared to women with fatty breast tissue.
Breast density masks the appearance of cancer
Breast density plays a significant role in the ability of mammograms to detect early breast cancer. Fat looks dark on a mammogram, but both dense breast tissue and cancer appear white. Therefore, on a mammogram, a cancer can easily hide in a background of dense breast tissue because they both appear white. According to research, 35% of breast cancer goes undetected by mammography alone in women with dense breasts, as density masks the appearance of tumors.
Screening technology for dense breast tissue
Mammograms remain the gold standard tool for screening, but they do not work equally well in all women. As a result, women with dense breast tissue may need additional tests. Studies have shown that certain supplemental imaging exams, such as breast ultrasound, improve the sensitivity of detecting cancer when used together with mammography. On ultrasound, tissue appears black and cancer appears white, helping make it more visible to the radiologist. An emerging technology for screening women with dense breasts is automated breast ultrasound (ABUS).
