Longer follow-up evaluating digital breast tomosynthesis (DBT), also referred to as 3D mammography, demonstrates its continued effectiveness compared to standard digital mammography (DM) when screening for breast cancer. These results were recently published in JAMA Oncology.
It is well established that survival rates for treatment of early breast cancer are significantly superior to survival rates of breast cancer once it has spread to distant sites in the body. Despite this, controversy exists over optimal screening methods, timing, and patient age so that the benefits of screening are maximized, while the potential harms of screening are minimized.
An area of great concern regarding any type of screening includes the rate of false-positive readings of the screening measures. A false-positive reading refers to a screening result that appears suspicious for cancer, requiring follow-up procedures to determine if cancer exists. If it is a false-positive reading, it means that the final results indicate that suspicious area is benign (non-cancerous).
In regards to mammography, the follow-up for a suspicious result can be an additional mammogram, ultrasound, or other type of imaging of the breast, and/or a biopsy. Follow-up procedures are associated with patient anxiety, increased medical costs for subsequent procedures, pain (particularly for a biopsy), scheduled time out of the day for the procedure, and/or even a scar from the biopsy.
In order to reduce false-positive readings that result in follow-up procedures, it remains imperative that researchers strive to provide screening measures that are as accurate as possible.
DBT has been approved by the United States Food and Drug Administration (FDA) as a screening measure for breast cancer. DBT layers additional images of the breast to DM, creating a 3D-visual image that allows radiologists to have a clearer view of the breast tissue.
Results leading to the approval of its use demonstrated that initial use of DBT decreases false-positive examinations, and increases cancer detection compared with DM. However, the long-term benefits of DBT are still under evaluation.
Switching from DM to DBT is associated with initial costs for the machine, as well as resources to instruct both technicians to use the machine, and radiologists to best read results. To justify these upfront costs, researchers continue to evaluate the use of DBT in the clinical setting.
Researchers from the Perelman School of Medicine at the University of Pennsylvania recently conducted a study to explore the longer-term implications of DBT compared to DM, beyond initial screening results. The study was an analysis of data including nearly 24,000 women over the course of 4 years – from 2010 through 2014.
In 2010, all women were screened with only DM. From 2011 through 2014, women received either 1, 2 or 3 screenings with DBT (depending upon how often they returned for regular screening through those years).
- Recall rates (percentage of patients requiring additional follow-up after screening) was significantly reduced with DBT compared to DM.
- The percentage of patients who were diagnosed with cancer among those recalled was significantly higher for DBT compared to DM (indicating superior accuracy of DBT readings).
- Interval cancers (a diagnosis of cancer within 12 months of screening) were reduced with DBT compared to DM.
The researchers concluded that “Digital breast tomosynthesis screening outcomes are sustainable, with significant recall reduction, increasing cancer cases per recalled patients, and a decline in interval cancers.” These results lend to increasing data indicating the superiority of DBT to standard DM as screening for breast cancer.
Reference: McDonald E, Oustimov A, Weinstein S, et al. Effectiveness of Digital Breast Tomosynthesis Compared With Digital Mammography. Outcomes Analysis from 3 Years of Breast Cancer Screening. JAMA Oncol. Published online February 18, 2016. doi:10.1001/jamaoncol.2015.5569.
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