MICHELE NORRIS, Host:
NPR's Patti Neighmond reports.
PATTI NEIGHMOND: Berg enrolled over 2,000 women at 21 different imaging centers across the U.S. These were women with the kind of breast tissue that can be challenging to find cancer using mammograms alone. The tissue is dense, and it shows up as white on a mammogram - the same color, says Berg, as cancer.
NORRIS: Ultrasound is a completely different way of looking at the breast tissue that is not at all limited by how dense the breast tissue is. It's just using sound wave to penetrate the breast tissue, and we see cancers because they're darker, usually, than the tissue around them.
NEIGHMOND: So in this study, ultrasound, in addition to mammography, picked up 28 percent more cancers than mammography alone. That's a lot, says Berg.
NORRIS: And the types of cancer that we see with ultrasound are still small, but they are invasive cancers. They're the type that spread when they're not detected. And in this study, we found that the vast majority of cancers we found with ultrasound had not yet spread to lymph nodes. And that's important. Those are the types of cancers that we need to be finding.
NEIGHMOND: Berg says these are cancers that could eventually show up as a lump in the breast - cancers that might also spread to lymph nodes. While these findings are important, Berg says there are some cautions. The ultrasound was four times more likely than the mammogram to find lesions or abnormalities that looked like cancer but were not.
NORRIS: That's a fairly substantial risk of an unnecessary biopsy. Now, for some women, they would still want to have a test because it certainly has a chance of finding cancer when it's still early and treatable. But for other women, that's too great a risk of a false positive, and they don't want to take that chance.
NEIGHMOND: Biopsies, of course, are a surgery which require anesthesia and carry some risk. Dr. Lawrence Bassett heads the UCLA Iris Cantor Center for Breast Imaging. Bassett says ultrasound should not be done routinely for all women. It should be done for women at high risk of breast cancer, those who have dense breast tissue, or have a close relative who was diagnosed with breast cancer before the age of 50. And if women are at even higher risk - for example, they or one of their close relatives carry the breast cancer gene - then, says Bassett, an MRI is recommended.
NEIGHMOND: And I mean women who have genetic changes or they've had previous biopsies that show very, very - lesions that tend to put you at higher risk; they may have had breast cancer before and have a strong family history as well.
NEIGHMOND: Patti Neighmond, NPR News.
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