Women have a few choices when it comes to screening for breast cancer. They can test with mammograms printed on X-ray film, digital mammography or with a newer imaging technology called digital breast tomosynthesis (DBT). In many screening centers, digital mammography, or two-dimensional (2-D) mammography, has actually replaced X-ray film mammograms.
Recent development: A growing body of research suggests that DBT, also known as three-dimensional (3-D) mammography, may provide better results than standard digital mammography. Now, a new study comparing digital mammography against DBT supports DBT as the better screening method for breast cancer.
Digital mammography allows the radiologist to make X-ray images darker or lighter—this helps find breast cancer, especially in dense breasts. These images can be viewed on a computer and the images can be made larger to focus on specific areas. DBT also uses computer imaging, but the images are taken as a camera arcs over the breasts taking pictures from different angles. This allows for a 3-D image and eliminates overlapping breast tissue that can hide a cancerous tumor.
Studies show that DBT misses fewer cancers than digital mammography. If a screening exam does not find a cancer (a negative exam), but a cancer is found within the following year, the exam is called a false negative. It’s been shown that DBT provides a lower rate of false-negative exams, which may mean screening with DBT can find cancers earlier and increase survival because these cancers are less advanced and easier to cure.
Research details: To compare false negative results from digital mammography versus DBT, researchers from 10 academic and community screening centers reviewed more than 380,000 screening exams. The exams were divided almost equally between digital mammography and DBT. These were the key findings…
- DBT had a false negative rate of 0.6 per 1,000 exams compared with a rate of 0.7 for digital mammography.
- DBT had a higher sensitivity rate (89.8%) than digital mammography (85.6%). Sensitivity indicates how likely a test is to detect a condition when it is actually present in a patient.
- DBT had a higher specificity rate (90.7%) than digital mammography (89.1%). Specificity is the ability of a test to rule out the presence of a disease in someone who does not have it.
- DBT had lower odds of missing an advanced cancer than digital mammography.
Takeaway: Based on its improved sensitivity, specificity and ability to detect invasive cancers before they spread, screening with DBT is superior to digital mammography, according to this study. The researchers anticipate that DBT will eventually become the standard of care for breast cancer screening.
Source: Study titled “False-Negative Rates of Breast Cancer Screening with and without Digital Breast Tomosynthesis,” led by researchers at Yale School of Medicine, New Haven, Connecticut, published in Radiology.