Why it's done

A 3D mammogram is used as a breast cancer screening test to look for breast cancer in people with no signs or symptoms of the disease. It can also be used to investigate breast problems, such as a suspicious lump or thickening.

When used for breast cancer screening, the 3D mammogram machine creates 3D images and standard 2D mammogram images because both types of images have some advantages in seeing certain breast abnormalities.

Combining a 3D mammogram with a standard mammogram can:

• Reduce the need for follow-up imaging. When doctors detect abnormalities on standard mammogram images, they may recommend additional imaging. Being called back for additional imaging can be stressful. It may take extra time and lead to additional costs. Combining a 3D mammogram with a standard mammogram reduces the need for follow-up imaging.
• Detect slightly more cancers than a standard mammogram alone. Studies indicate that combining a 3D mammogram with a standard mammogram can result in about one more breast cancer for every 1,000 women screened when compared with standard mammogram alone.

• Improve breast cancer detection in dense breast tissue. A 3D mammogram offers advantages in detecting breast cancer in people with dense breast tissue because the 3D image allows doctors to see beyond areas of density.

  Breast tissue is composed of milk glands, milk ducts and supportive tissue (dense breast tissue) and fatty tissue. Dense breasts have greater amounts of dense breast tissue than fatty tissue. Both dense breast tissue and cancers appear white on a standard mammogram, which may make breast cancer more difficult to detect in dense breasts.

There isn't enough evidence to conclude that 3D mammograms can reduce the risk of dying of breast cancer more than a standard mammogram alone. For this reason, most guidelines for breast cancer screening don't specify that women should choose 3D mammograms over standard mammograms alone.