Alternatives in Breast Cancer Screening
By Vilert Loving, MD is a board-certified radiologist who specializes in breast diseases at Banner MD Anderson Cancer Center.
Question: Two of my close relatives have had breast cancer. I hear there are new screening options besides mammograms. What are they, and do they provide better diagnosis of early breast cancer?
Answer: One new breast cancer screening option is 3D tomosynthesis. Instead of the two-dimensional image we acquire with traditional mammography, tomosynthesis gives us a three-dimensional picture of the breast. One way to understand this is to imagine the breast as a book. With 3D tomosynthesis, we are essentially able to turn the pages and see the different layers of the breast. This means we can see more depth and detail and better evaluate abnormalities. Tomosynthesis is performed with a woman in the same position as for a traditional mammogram. The arm of the machine moves in an arc over the breast, taking multiple additional pictures.
Preliminary studies of 3D tomosynthesis indicate that it provides a slight improvement in the cancer detection rate compared to traditional mammograms. Additionally, it allows us to better identify normal breast tissue, so we report fewer false positives. This saves women the anxiety of having to return for additional pictures. Some studies have shown a 20 to 40 percent decrease in false positives using tomosynthesis.
Tomosynthesis is a better diagnostic tool for women with dense breasts. Dense breasts can make cancer difficult to detect, and some studies suggest that having dense breast tissue increases women’s risk of developing breast cancer. Tomosynthesis improves our ability to look through the dense breast tissue and identify cancer.
Breast MRI has been available at some facilities for several years. MRI is superior to mammography in detecting breast cancer, but also finds more noncancerous lesions. The composition of the MRI images can make it difficult to determine if an abnormality is cancerous, leading us to refer women for biopsies — many of which are negative. For this reason, we only recommend MRI for women who are at high risk for breast cancer. MRI is used as a supplement to mammograms, not a replacement.
Many women are concerned about radiation exposure during breast screenings. Although 3D tomosynthesis doubles the radiation exposure of traditional mammograms, the exposure is still very low. For both traditional mammography and tomosynthesis, exposure is well below the radiation dose a woman would expect to receive from annual natural background radiation. Some newer tomosynthesis machines have lowered the radiation dose to be equivalent with traditional mammograms. MRI has zero radiation exposure.
3D tomosynthesis and breast MRI are available at many Banner facilities. Women should ask their physician which screening is best for them based on their family history and other breast cancer risk factors.