Mammogram: Can it find cancer in dense breasts?

Dense breasts can make traditional mammograms more difficult to interpret. But this doesn't mean a traditional mammogram is useless for detecting cancer or other breast abnormalities in women with dense breasts.

Breast tissue is composed of fatty (nondense) tissue and connective (dense) tissue. The relative ratio of fatty tissue to connective tissue differs among women. As women age, their breasts tend to become less dense.

Dense breast tissue appears as a solid white area on a mammogram film, and fat appears as a dark area. Mammogram X-rays do not penetrate — or "see through" — dense tissues as well as they do through fat. So, in women with dense breasts, mammograms are more difficult to interpret. Tumors also are dense tissue and appear as solid white areas on the mammogram. This can make it more difficult to detect a tumor in dense breasts because it looks a lot like the dense tissue that surrounds it. It's not clear why some women have denser breast tissue than do others.

Some studies have found that newer digital mammography does a better job detecting cancer in dense breasts than does traditional mammography. A digital mammogram produces images on a computer screen that can be enhanced and magnified for closer viewing. However, digital mammograms aren't as widely available as are traditional mammograms. Also, some insurance companies won't pay for the more expensive digital mammograms.

Make an appointment with your doctor if you notice any worrisome breast signs or symptoms, such as a lump or nipple discharge, even if a recent mammogram was normal. Your doctor may recommend other imaging tests, such as a breast ultrasound, to further investigate a breast abnormality.