Medically Reviewed by W. Shawn Conwell, MD, FACR
“Dense breast” does not refer to size. A woman’s breast – small or large – can have a high percent of fat compared to breast tissue, making it difficult to spot breast cancer. Radiologist W. Shawn Conwell, MD, FACG, explains the challenge.
Here’s a summary of Dr. Conwell’s discussion:
“Dense breast tissue” is an observation that we make on a mammogram as radiologists. So, when we look at the mammogram, there is fat, which is black on a mammogram. And there’s breast tissue, which is white on a mammogram. So, the degree of relative whiteness to blackness is what we describe as breast tissue density. Density matters, because as breast tissue density increases, our ability to see breast cancer on the mammogram decreases. I like to say it’s like looking for a polar bear in a snowstorm. The breast cancer shows up as white, so if you’re looking through a white background, making tumors very difficult to see.
In women with the densest breast tissue, we have the highest likelihood of missing breast cancer, if it were to exist. Approximately 40% of women can be described as having dense breast tissue.
The density of breast tissue can only be determined on a mammogram. You cannot determine breast tissue density by size, shape, feel, physical exam or any other feature. There are some small-breasted women as well as some large-breasted women, who have “fatty” breasts. The way to tell breast tissue density is to get a mammogram.
Ideal imaging for dense breast tissue is really controversial. There are no clear cut guidelines as to exactly how to image those women, but radiologists have known for a long time that mammography is limited in women with dense breast tissue.
3D mammography does help overcome that tissue density problem quite well. However, there are still concerns, particularly with the extremely dense category. What we often do in those circumstances is invite women to undergo ultrasound screening. The ultrasound is not limited by the issue of breast tissue density.
If a woman has a greater than 20% lifetime risk due to a family history of breast cancer, then we recommend she undergoes MRI screening. We know that if a woman is undergoing MRI screening, she does not also need to undergo ultrasound, but she does need to undergo mammography.
The concern that we have as physicians is that if a woman doesn’t know what her density is, then she can’t have those conversations. That’s is one reason that Hope’s Law was passed in South Carolina. The law states that we should notify all women of their breast tissue density and, when they are dense, include a phrase that suggests essentially a conversation with their physicians.
To schedule a mammogram, call 843-777-2095, select option 1.
Have a question? Ask a Cancer Specialist.