Will 3-D mammograms improve cancer care?

Some experts say it's too soon to say if the technology will improve detection

Breast tomosynthesis may detect cancer better than conventional mammograms, but it's still unclear whether widespread use of the technology will improve patient outcomes, Nancy Shute reports for NPR's "Shots" blog.

Why 3-D mammograms could revolutionize breast cancer care

Standard mammograms, which involve a vertical and horizontal image of each breast, miss about 20% of cancers, according to the National Cancer Institute. By comparison, breast tomosynthesis—a 3-D mammogram technology approved by the FDA in 2011—swings the X-ray machine in an arc to take about 60 pictures. The radiologist can view the images like a "digital flipbook," increasing the odds of detecting small tumors, Shute explains.

Evidence suggests added benefit

Research presented Tuesday at the Radiological Society of America meeting in Chicago touted the 3-D technology's superiority in detecting cancer. The study compared 15,633 women who had 3-D scans at the University of Pennsylvania Medical Center in 2011 to 10,752 women who underwent standard digital mammograms at the hospital the year prior.

The researchers found that the 3-D screening increased cancer detection rates from 4.28 to 5.24 per 1,000 patients. At the same time, the technique reduced false positives from 10.40% to 8.78%.

"It's an exciting platform," lead author Emily Conant told Shute, adding, "It really addresses a lot of the criticism of screening mammography by the U.S. Preventive [Services] Task Force and others." The panel in 2009 advised against mammograms for women under age 50, citing the high rate of false positives which lead to unnecessary anxiety and additional testing.

Do 'modest' benefits outweigh time, expense?

However, some experts maintain that there's been little hard evidence to support the claim that 3-D mammograms are more useful than standard detection methods or to determine which patients might benefit. As a result, insurers have shied away from covering the procedure, leaving patients with $50 to $100 in out-of-pocket costs.

"The gains seem to be modest in both directions," says Carol Lee, a radiologist at Memorial Sloan-Kettering Cancer Center, adding, "Is this something that will prove to be worth the additional time, expense and radiation exposure?" She says the latest findings are "encouraging, but it's not the definitive study."

Women with dense breast tissue are widely expected to benefit the most from the new technology because 2-D mammograms are not great at detecting tumors through dense tissue. However, research to date has not proven that this group of patients benefits more from the technology. 

"We need to wait and see if the next round shows the same benefit, and whether we can figure out if it's for everybody, every year," says Barbara Monsees, a professor of radiology at the Washington University School of Medicine in St. Louis (Shute, "Shots," NPR, 12/3).

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