Having a mammography after the age of 40 is something any woman should do to be sure they are not at risk of having breast cancer. Unfortunately, mammography alone appears to be inefficient sometimes, according to new research, which suggests that mammography should be combined with ultrasound exams in order to detect breast cancer more accurately.

Although death rates from breast cancer have been declining, possibly due to earlier detection and diagnosis, on a national level, breast cancer still represents the second leading cause of cancer death for women. The first cause is lung cancer. According to the American Cancer Society, more than 180,000 American women are diagnosed with breast cancer every year, and almost 41,000 will die because of it.

The new study involved almost 3,000 women (recruited from 21 centers) with an average age of 55 and a higher-than normal risk of breast cancer. The women were randomly assigned to receive either mammography alone or mammography plus ultrasound performed by a physician.

The study showed that, after a year, a mammogram alone found 7.6 cases of cancer per 1,000 women screened, while adding an ultrasound bumped the detection rate up to 11.8 cases per 1,000 women.

“Mammograms saw only half of the breast cancers that were present. If we added ultrasound to mammography, we saw 78 percent of the cancers,” said Dr. Wendie Berg of American Radiology Services at Johns Hopkins at Green Spring Station in Lutherville, Md., who did the study, the New York Times reports.

However great the benefits of the study were, they were balanced by more false-positive readings. More specifically, when only a mammogram was used, one in 40 women had an unnecessary biopsy to check for cancer. When the ultrasound was added to the equation, one in 10 women had an unneeded biopsy.

Dr. Berg concluded: “The detection benefit of a single screening ultrasound in women at elevated risk of breast cancer is now well validated, but the high false positive rate and the lack of screening ultrasound for breast cancer will likely limit its role as a screening tool. There is a shortage of trained personnel, so if everybody decided tomorrow to use ultrasound to screen for breast cancer, that couldn’t happen,” Dr. Berg told WebMD.

In an editorial accompanying the study in the May 14 issue of the Journal of the American Medical Association, radiologist Christine Kuhl, MD of the University of Bonn writes that although mammography has been used for more than four decades, it may be a good time now to reconsider. “Whether in the long run, ultrasound or breast MRI will be more appropriate for this purpose remains to be seen.”

However, given limited number of personnel specialized in ultrasound, Kuhl says “mammography will probably remain the basis for breast cancer screening for the foreseeable future” although increasing evidence suggests that for many women , “mammography does not provide the best possible accuracy.”

This adds to the fact that the accuracy of a diagnostic in reading a mammogram depends on the radiologist’s ability to detect cancer, as a study published in the Journal of the National Cancer Institute last December suggests. It was found then that the accuracy of detecting cancer ranged from 27 percent to 100 percent and the false-positive rate ranged from zero to 16 percent. The most accurate radiologists were the ones from academic medical centers.

According to the American Cancer Society, women with the highest risk for breast cancer should undergo annual screening with magnetic resonance imaging (MRI) in addition to mammography.

The Avon Foundation and the National Cancer Institute funded Dr. Berg’s study.