WEDNESDAY, Oct. 1 (HealthDay News) -- When it comes to reading mammogram results, two heads aren't always better than one.

A new study found that so-called computer-aided detection (CAD) for screening mammography has rates of cancer detection similar to mammograms read by two different radiologists.

"Reading mammograms by a single reader (radiologist) using CAD has been shown to be as clinically effective as having films read by two expert readers," said the study's lead author, Dr. Fiona Gilbert, a professor of radiology at the University of Aberdeen in the United Kingdom.

"Women should be reassured that the final decision on recall is made by the human reader using their knowledge and experience to decide if any areas of the mammogram marked by CAD merit further investigations," she said.

In the United Kingdom and many European countries, the recommendation is that every mammogram be read by two independent radiologists. This practice isn't common in the United States, according to Dr. Thomas Hall, director of breast imaging for Providence Hospital in Southfield, Mich. "Most mammograms are single-read in America, though most places now, when they get digital mammography, also get CAD," he said.

Gilbert said, "We know that two readers will detect approximately 10 percent more cancers than a single reader." But two readers aren't always available. Sometimes, there might be seasonal shortages, as might occur during the holidays. Or, it may be that there aren't enough resources to have multiple radiologists available to read mammography results, she said.

So, Gilbert and her colleagues wanted to know if the computer plus one reader would be similarly effective to two readers.

To assess this question, the researchers randomly assigned more than 31,000 women undergoing routine screening mammography to have their films read by two radiologists, by CAD and one radiologist, or using both measures.

Double reading found 87.7 percent of the cancers, while CAD plus a single reading was able to detect 87.2 percent. Recall rates, that is the number of women called back for further testing due to suspicious findings, were 3.4 percent for double reading and 3.9 percent for single reading with CAD.

The study findings were expected to be published in the Oct. 16 issue of the New England Journal of Medicine, but were posted online Oct. 1.

"CAD could increase the cancer detection rate of a single reader in breast screening centers currently using single reading alone," said Gilbert, who added that, "in countries where double reading is standard practice, CAD could be used if there is a shortage of readers without compromising cancer detection rates."

Hall said it's likely that, if this study had been done with a digital mammography system, the results would have been even better. He said for this study, the researchers took mammography films and scanned them into the computer before the computer reading. That means the computer was essentially checking a copy, and when you copy something, information may be lost, he said.

"There are definite advantages to digital mammography with CAD. Digital helps you visualize the anatomy better, and the CAD helps keep you on your toes," Hall said.

More information

To learn more about mammography, visit the Radiological Society of North America.