New screening tests for hard-to-spot breast cancers

Millions of women in 21 states will get an ominous note with their mammogram results this year. Even if everything seems fine, they’ll be informed that they have dense breast tissue, which can raise their risk for cancer and hide abnormalities, making their mammograms less accurate.
The question is: now what?

 

A host of new breast-imaging technologies promise to detect more cancers in these women. But many of the methods bring more false alarms as well, subjecting women to additional tests and biopsies unnecessarily. Some are also more expensive than mammograms and haven’t been widely studied yet.
Laws in 21 states require doctors to tell women they have dense tissue. Similar bills are pending in eight more states and a national bill was introduced in Congress earlier this month.
“It’s a very confusing time,” says Emily Conant, chief of breast imaging at the University of Pennsylvania Medical Center. “This legislation has happened before we have a medical consensus about what to tell women.”
Some experts say telling women they have dense breasts would make them anxious unnecessarily.
“Of course you might be anxious. But I’d trade a false positive for a false negative any day,” says Nancy Cappello, who started the campaign for density-notification laws and the organization Are You Dense? after numerous mammograms failed to spot her advanced breast cancer. Doctors had noted her dense breasts for years, but never told her that her mammograms might not be showing potential problems.

As of now, mammograms are the only breast-screening technology proven to save lives, experts say. Every year, some 40 million U.S. women undergo a mammogram, in which their breasts are compressed between metal plates and X-rayed from top to bottom and side to side. Cancerous tumours and even tiny calcifications that can indicate early cancers show up as white areas on the images, distinct from fatty breast tissue. But breast tissue that is glandular and fibrous appears white, too, and can obscure such abnormalities.
About 50% of women under age 50 and 33% of older women have breasts dense enough in some spots or throughout to interfere with mammograms, studies show. Mammograms can miss up to half of early cancers in such women.
Digital mammography—in which images are stored digitally rather than on photographic film—are more accurate, because the images can be enlarged and enhanced. But they still miss about 20% of cancers in women with dense breasts, studies show.
More hospitals and imaging centers now offer a new form of mammogram called 3-D tomosynthesis. It starts like a regular two-dimensional mammogram. Then the X-ray arm rotates around the patient in an arc, taking additional images at different angles that can be assembled into a three-dimensional view. Radiologists liken 3-D tomosynthesis to taking pictures of the individual pages of a book, rather than trying to see what’s inside by just the front and back.
In a study of nearly 500,000 women at 13 centers published in the Journal of the American Medical Association last year, 3-D tomosynthesis found 41% more instances of invasive cancer than regular mammography, and had 15% fewer false positives.
“We do tomo on every woman who comes into our centre. It’s definitely becoming the standard of care,” says Dr. Conant, one of the investigators on the JAMA study. Still, she notes, that study didn’t look specifically at women with dense breast tissue.
Ultrasound does find more cancers—but about four times as many false positives as well. An analysis in the Annals of Internal Medicine in December estimated that ultrasound screening, in addition to mammograms, would avert four breast cancer deaths for every 10,000 women aged 50 to 74 with dense breasts. But it would also result in 3,500 biopsies that didn't find cancer and cost an additional $10 million. The authors, including breast-cancer researchers at 14 major medical centres, concluded that supplemental ultrasound would increase costs substantially while producing relatively few benefits.
Some doctors—and many women with dense breasts—disagree, and say ultrasound found life-threatening cancers that mammograms routinely missed.
“Women are strong. We need this information,” says Claudia White, 48, of Durham, Conn., who credits the state’s first-in-the-nation notification law with prompting the ultrasound that found invasive cancer in both of her breasts. Connecticut’s law also requires insurers to cover the cost of supplemental ultrasound (generally $50 to $150) for women with dense breasts.
“I’d rather be scared for a couple of days than dead,” says Jan Kritzman, 67, of Newington, Conn., whose cancer was also diagnosed on ultrasound thanks to the state’s law.
MRI—magnetic resonance imaging—finds even more cases of breast cancer, with fewer false positives, than ultrasound. But because it is time-consuming and costly—as much as $1,500 in some centres—it is generally recommended only for women who are at high risk for breast cancer.
Some researchers are testing whether an abbreviated version—called “fast MRI”—can achieve the same results by taking only a few images, in far less time, and cost just $200 to $300, about the same as ultrasound.
Molecular breast imaging or MBI, also holds promise. It involves injecting a radioactive tracer into the patient’s vein. Cancer cells readily absorb the substance and “light up” when viewed with a special camera.
Past versions of MBI exposed patients to too much radiation to use for regular screenings. A new version developed at the Mayo Clinic in Rochester, Minn., uses a lower dose. In a study of 1,585 women with dense breasts published in the American Journal of Roentgenology this month, Deborah Rhodes, a Mayo Clinic internist, and colleagues found that MBI detected nearly four times as many invasive breast cancers as mammography, with fewer unnecessary biopsies. As of now, only about 100 hospitals offer the newest MBI technology, which is made by GE Healthcare and Gamma Medica Inc. But with costs as low as $300, it could grow rapidly, particularly if additional studies yield similar results. Mayo receives royalties from one manufacturer, Gamma Medica Inc.
Doctors say that a large, randomized clinical trial comparing all the options for women with dense breasts would be helpful. Meanwhile, they can help women understand the pros and cons and decide for themselves whether to seek additional tests.
Some say that given the uncertainties, they wish they didn’t know their breasts were dense. Denice Newton, 52, had a biopsy last year after getting a notice under North Carolina’s new law. Even though it was negative for cancer, she hated the ordeal. “Mentally, I was planning my funeral,” she says. “Now, every time I feel an itch or soreness in my left breast, I think, ‘Cancer.’ “I do not want to go back in six months, but I’m afraid if I don’t, I might regret it.”

Source; The wall street journal