Some women have very dense tissue in their breast, so mammograms are harder to read and cancers are harder to find. Now, a new study suggests adding a second test for women with dense breast tissue may improve cancer detection.
The images produced by a mammogram show the tissue inside the breast. And in most breasts, the cancers can be clearly spotted.
But when that tissue is dense, cancers can remain unfound.
"The cancers can be hidden by the normal breast tissue," Johns Hopkins radiologist Dr. Wendie Berg said. "It's been likened to trying to find a polar bear in a snow storm."
Bonnie Ostrowski had dense breast tissue, so when doctors added ultrasound to her mammography, a cancer was found.
She was treated and has now been cancer-free for seven years.
"I really do believe that the ultrasound did help save my life," she said.
Dr. Berg studied more than 2,000 women with dense breast tissue. Each had both mammography and ultrasound.
"Mammography did pretty well, but it did miss a large number of cancers," she said. "Only half of the cancers present were actually seen on mammography."
Forty women were diagnosed with cancer. Twenty of those cancers were revealed with mammography. Twelve more were found when sonogram was added. Eight cancers went undetected by both mammography and ultrasound.
"The overall performance of mammography, we had an accuracy of 78 percent," Dr. Berg said. "If we added ultrasound to that, the overall accuracy was much better, at 91 percent."
However, ultrasound does add a risk of unnecessary biopsy. And it's not recommend as a solitary test.
"I've had requests from patients to have only an ultrasound," Dr. Berg said. "That's not appropriate, because there are many cancers that are not seen on ultrasound."
The story will be published in Wednesday's Journal of the American Medical Association.
