PITTSBURGH, Dec. 29 (UPI) -- Mammograms and ultrasounds are equally effective at detecting breast cancer, especially node-negative invasive forms, researchers report in a new study.
While ultrasounds were found to give more false positives, they can detect harder to find cancers and are more widely available in developing countries.
In the United States, the cost for both procedures is similar. Researchers in the study said ultrasound should be used as a supplemental screening for breast cancer, though insurance policies vary from state to state, where supplemental screening for women with denser breasts or other increased risk factors may not be required by law and so are not covered.
"The issue is: what are the cancers we most need to find," Dr. Wendie Berg, professor of radiology at the University of Pittsburgh Medical Center, told HealthDay. "The cancers you need to find are the invasive, node-negative ones. More of the cancers found with ultrasound were invasive and node-negative than those found with mammography."
In the study, published in the Journal of National Cancer Institute, researchers enrolled 2,809 participants in the United States, Canada and Argentina. Of the participants, 2,662 had three annual screenings, 4,351 of which were ultrasound and 3,122 were mammograms, as well as a biopsy or 12-month follow-up.
Of the women in the study, 111 had breast cancer events, 80.2 percent of which were invasive with a median tumor size of 12 millimeters. The researchers found about the same number of mammograms and ultrasounds detected cancer, but ultrasound-detected cancer was more likely to be invasive and node-negative. Among these, however, false positives were more common with ultrasounds.
"For U.S. patients, what [this study] really confirms is ultrasound should be used as a supplemental screening exam in dense breast patients," said Dr. Lusi Tumyan, a radiologist and assistant clinical professor at the City of Hope Cancer Center. "At this time we do not have enough data to support or refute ultrasound as a screening tool for average-risk patients."