Computerized devices used to assess 30 percent of mammograms in the U.S. offer less accurate results than those produced by radiologists on their own, while raising costs by as much as $70 a test, researchers said.
A study showed that use of computer-aided detection, or CAD, increased "false positive" results and biopsies without improving identification of serious cancer.
Mammogram facilities have steadily adopted CAD since the U.S. Food and Drug Administration approved the technology in 1998. Setting up a CAD system can cost a medical center as much as $675,000 and adds an additional $70 to the cost paid out by Medicare per mammogram. That compares with as much as $150,000 for a conventional unit, researchers said.
"It looks like computer-aided detection might not be working like people thought it would," said lead researcher Dr. Joshua Fenton, a family doctor at the University of California-Davis, in Sacramento.
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The findings, which appeared Thursday in the New England Journal of Medicine, touch on a rapidly spreading technology first marketed in 1998.
CAD consists of a computer coupled with software that identifies suspicious spots on mammograms and marks them.
When mammograms are taken, radiologists first read the X-rays and make their own judgments. But then they double-check with the computer system to see if they have missed anything worth examining further.
There usually isn't. Still, some studies have shown that CAD can turn up 10 percent to 20 percent more cancers. Patients often have no idea if this new technology is being used.
The researchers in this five-year study — backed by the federal government and the American Cancer Society — analyzed mammograms from medical centers in Washington state, Colorado and New Hampshire. Seven of 43 centers used CAD. The mammograms came from 222,135 women and included 2,351 with a cancer diagnosis within a year of their tests.
The researchers found that with computerized mammography, a third more women were called back for suspicious findings and 20 percent more got biopsies than with ordinary mammograms. But the computerized method showed no capability to turn up more cancer cases than unaided readings.
at a glance
Healthy women should begin getting mammograms every year or two once they reach age 40, experts say. Here are tips from the American Cancer Society and other experts:
• Find an experienced, high-volume center with accomplished radiologists. You can ask for their credentials.
• Ask to see the certificate showing the center is approved by the U.S. Food and Drug Administration.
• Use the same center regularly, so it's easier to compare your new mammograms with your old ones.
• Bring a list of places you've had mammograms, dates, biopsies, or other breast treatments. Bring old mammograms or have them sent.
• Describe any breast problems to the person doing the mammogram. Be ready to give past surgeries, hormone use, and family or personal history of breast cancer.
• Call your doctor or center to check on the mammogram if you hear nothing within 10 days. Don't assume everything was normal.
