Breast ultrasound: Better screening for more women?
January 4, 2016
| by Abe Rosenberg
A just-released study
suggests that ultrasound can be as effective as mammograms in detecting breast cancer in women, and even more accurate in some cases.
The study's authors conclude that ultrasound should play an important role, side-by-side with mammograms, for the estimated 50 percent of American women with dense breast tissue.
The new ultrasound study
, published in the Journal of the National Cancer Institute
, looked at 2,809 women in the U.S., Canada and Argentina. None of the participants had any symptoms, but they all had dense breast tissue, which is believed to be a risk factor for breast cancer.
Almost all of the women underwent three annual screenings involving ultrasound and mammography. Researchers found that ultrasound detected roughly the same number of cancers as mammography. Ultrasound also found a greater number of more dangerous, invasive cancers.
Mammograms have long been the gold standard for breast cancer detection, but they're not perfect: They expose the patient to radiation. They are less effective in women with dense breasts, which contain more glandular and connective tissue than fat. And in many parts of the world, mammograms are financially out of reach, or simply unavailable.
"Where mammography is available, ultrasound should be seen as a supplemental test for women with dense breasts who do not meet high-risk criteria for screening MRI, and for high-risk women with dense breasts who are unable to tolerate MRI,” said Wendie A. Berg, Ph.D., the study's lead author.
In an interview with HealthDay.com
, Lusi Tumyan, M.D., chief of the Breast Imaging Section at City of Hope (who was not affiliated with the study), echoed this sentiment, pointing out that “mammography is less sensitive in patients with dense breast (tissue). Ultrasound in this patient population is a great supplemental examination that is also affordable.”
Like other screening methods however, ultrasound also has limitations. Accuracy can depend on the skill of the operator, unless the process is automated, a relatively new option. Ultrasound is generally less adept at detecting abnormalities such as calcification, and there is a reported higher rate of false positives: During the first year of the study, 9 percent of biopsies that were ordered based on ultrasound findings confirmed the presence of cancer, compared to 29 percent of biopsies ordered for positive mammograms.
California is one of 21 U.S. states that require women to be notified when dense tissue is seen on a mammogram. Some states also require supplemental screening, like ultrasound, even if the mammogram found no cancer. California does not mandate a second screening and most insurers won't pay for it if the mammogram is clean.
So what's the best course? Should ultrasound be a routine second test, in addition to mammography?
Nikita Gidwaney, M.D., assistant clinical professor in the Department of Diagnostic Radiology at City of Hope, calls ultrasound a “synergistic” test for breast cancer detection, and says personalized screening is one way to approach the matter. To that end, she recommends that all women should know their family history as well as their specific breast density.
Gidwaney would also like to see ultrasound become more robust. “I would like to see features such as elastography, better evaluation of blood flow patterns, and improvement of image resolution, use of contrast agents, and maybe down the line even fusion imaging, where a combo image is made using mammography and ultrasound.” Gidwaney said. She is also a strong advocate of 3D mammograms which provide more accurate images.
Until then, a decision on ultrasound may come down to the individual and her doctor, after a frank discussion of risks, benefits, and costs.
“At this time we do not have enough data to support or refute ultrasound as a screening tool for average-risk patients,” Tumyan told HealthDay.com
. She recommends women discuss their specific risks with their doctor and decide together which screening tests are appropriate.
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