Mammograms Miss Cancer in Dense Tissue

Dense tissue appears white on a mammogram. So do tumors.

That overlap can make it harder to detect breast cancer early, especially in women with dense breasts. What looks like a clean scan might not be the full picture.

Nearly half of women over 40 have dense breast tissue yet many aren’t aware of how it affects their screenings or their risk. In 2023 the FDA began requiring mammography centers to inform patients about their breast density, recognizing how it can complicate detection and delay diagnosis.

Dense breast tissue presents two challenges. First, it makes it harder for radiologists to identify tumors during routine screening. Second, it increases the risk of developing breast cancer. A study published in JAMA Oncology found that women with extremely dense breasts are four to six times more likely to develop breast cancer than women with mostly fatty tissue.

Dr. Wendie Berg, Professor of Radiology at the University of Pittsburgh, explained in an interview with Contemporary OB/GYN that dense tissue not only hides tumors but is also an independent risk factor for breast cancer. This makes screening decisions more complex and more important to individualize.

Additional tools like ultrasound and MRI can help detect cancers that mammography might miss. A review published in Insights into Imaging by the European Society of Radiology found that supplemental screening improves detection in women with dense breasts. Despite this, not all patients are offered additional imaging and insurance coverage often varies depending on state law or provider discretion.

Breast density is not a diagnosis but it is a clinically relevant factor that influences how screening is interpreted and what options might be recommended.