The radiologist says you have dense breasts. What does that mean?

About 40%-50% of all women age 40 and older who get mammograms have dense breast tissue. 

You often cannot feel it, but your radiologist can see it.

"On a mammogram, it looks like a cloud," says Cancer Treatment Centers of America Atlanta chief of surgery Dr. Anita Johnson.

She says the only way to know if you have dense breasts is to get a  mammogram.

"Most breast tissue is like a combination of fatty replace tissue and fibrous tissue," Dr. Johnson says.  "So, very dense breast tissue just means you have lots of fibrous tissue."

You are more likely to have dense breasts if you have a family history of dense breast tissue, are younger, have a lower body mass index, or you are using menopausal hormone therapy.

Women who are older or have had children may have more fatty breast tissue.

"In most cases, there's nothing you can do about it," Dr. Johnson says.  "It's just the way that you were born, and it's just part of your body."

Dense or fibrous breast tissue shows up gray or white on a mammogram, making it harder for the radiologist to see abnormalities, such as calcifications or tumors, which are also gray or white.

And, while dense breast tissue is normal, and common, the National Cancer Institute says women with dense breasts have a higher risk of breast cancer than women with fatty breasts, although it is not clear why.

There are several ongoing research studies into the link between breast density and cancer risk. 

Under Georgia law, mammogram providers are required to notify patients with dense breasts by letter, which Dr. Johnson says, could help you get insurance to cover any additional follow-up imaging you might need.

If you have dense breasts, Johnson recommends talking to your doctor about what that might mean for you.

"Go over your risk factors," Dr. Johnson says.  "If the radiologist recommends additional imaging, such as an ultrasound or breast MRI, usually they can support it with that diagnosis of dense breast tissue. And your insurance companies will be more lenient in getting it paid for."

And, if you get a call back after your mammogram, for another look at your breast tissue, Johnson says, don't panic.

"Less than 50% of the time is it something that you need to be concerned about, either as a pre-cancerous lesion or cancer," she says. "So, most callbacks are non-cancerous."

To read more about breast density,