A new study finds that adding screening ultrasound to routine mammography finds more cancers than mammography alone in women with dense breasts at increased risk for breast cancer. It also leads to a jump in false positives and unnecessary biopsies shows the research published in the Journal of the American Medical Association.
The Good News
“The study results confirm that screening ultrasound in combination with mammography detects more cancers than mammography alone,” says Wendie Berg, M.D, Ph.D., the study’s principal investigator and a radiologist at Johns Hopkins at Green Spring Station in Lutherville, Md. “Most were invasive, which are more aggressive, and hadn’t yet spread to the lymph nodes.”
The American College of Radiology Imaging Network (ACRIN) study, funded by the Avon Foundation and the National Cancer Institute, tracked 2,637 women ages 25-plus with increased breast cancer risk (criteria included dense breasts, prior atypical breast biopsy, personal and/or moderate family history of breast cancer).
Mammography alone found 50 percent of all discovered cancers, a detection rate of 7.6 women per 1,000 screened. Mammography and ultrasound combined found 78 percent of all discovered cancers, a detection rate of 11.8 women per 1,000 screened.
The False-Positive Risk
A false positive means an area of concern is seen in the exam that turns out not to be cancer. Mammography alone resulted in an unnecessary biopsy for one in every 40 women in the study; mammography/ultrasound together upped that number to one in 10.
“There’s a trade-off,” says Jeffrey Blume, Ph.D., the study’s statistician and deputy director of the ACRIN Biostatistics and Data Management Center at Brown University in Providence, R.I. “Ultrasound will find more things, but women have to be mentally prepared that they’ll more likely get a call back and have a biopsy they don’t need.”
For some women, says Berg, the stress can be too much. Others may be more pro-active and want to take action. Plus, screening ultrasounds are not widely available now or uniformly covered by insurance. “It's a personal choice, and women have to be informed of the risk,” she says.
Mammo vs. Ultrasound
Mammography uses low-dose X-ray and shows both dense breast tissue and tumors as white spots, making it hard to differentiate the two. Ultrasound screening uses high-frequency sound waves to detect tumors.
“The denser the tissue,” says Berg, “the harder it is to detect tumors. Small, invasive cancers are more likely to be missed by mammography.”
The American Cancer Society recommends that women at high risk for breast cancer be screened with magnetic resonance imaging (MRI) plus mammography. If you’ve had an MRI, you don’t need an ultrasound.
If you have dense breasts, ask your doctor about additional factors that determine your overall risk level for breast cancer. If you’re at increased risk, and undergoing mammography but not MRI, ask your doctor if adding screening ultrasound could benefit your health.