Adding an ultrasound to annual mammograms for women at higher-than-average breast cancer risk helps catch more early-stage tumors - but also ups the chance that healthy women will get follow-up biopsies unnecessarily, according to a new study.

For most women who fit into an “intermediate-risk” category - including those with very dense breasts, or who have a family member with breast cancer - the extra chance of false positives and more testing is probably worth it, said the study’s lead author.

That’s because along with those women’s higher chances of getting cancer, mammograms may not work as well on women with denser breasts, for example.

“The vast majority… of women who are well aware of these risks would still gladly choose to have the ultrasound, knowing that it increases the chance of finding cancer if it’s present and finding it early,” said Dr. Wendie Berg, from Magee-Womens Hospital in Pittsburgh.

Still, one researcher not involved in the study questioned whether that was feasible, or even a good idea.

Recommendations from cancer and radiology organizations call for women who are at high risk of cancer, including those with BRCA1 and BRCA2 gene mutations, to get magnetic resonance imaging (MRI) in addition to annual mammography.

But guidelines haven’t specified whether extra tests are also the best option for those in the intermediate-risk category - which may include up to 30 percent of women, Berg said.

“Anything that we propose to be extra in them, that’s a lot of women,” she told Reuters Health.

Berg said adding annual MRIs - which start at about $500 each - isn’t such a practical or cost-effective option, and many people feel claustrophobic during the procedure or just don’t like it. So she and her colleagues wanted to see if ultrasounds, which are less bothersome and run for under $100, might be an alternative addition to mammography.

Their study involved about 2,700 women seen at 21 different sites. More than half of those women had a history of breast cancer themselves - which also puts someone in the intermediate-risk category.

Every year for three years, women had both a mammogram and an ultrasound to check for signs of cancer. Finally, the researchers offered participants one MRI as a final check.

Over the study period, there were 111 new cases of breast cancer, 59 of which were picked up during mammography. Another 32 tumors that weren’t spotted on mammograms were found with ultrasound - 30 of which were invasive cancers, according to findings published in the Journal of the American Medical Association.

Out of 612 women who opted for MRI, nine more cancers that hadn’t shown up on other screening tests were detected. Eleven cancers were diagnosed at some point during the study through means other than screening.

A ‘SUBSTANTIAL RISK’ OF FALSE POSITIVES

Despite the additional cancers caught with ultrasounds and MRIs, there were downsides to the extra tests. One out of every 20 women had to have a breast biopsy because of ultrasound results, though only a small fraction of those ended up having cancer.

“It is a substantial risk,” Berg said.

“We are always in a quandary because we don’t know what to do with these intermediate-risk patients,” said Dr. Regina Hooley, who studies breast cancer screening at the Yale School of Medicine in New Haven.

“MRI is costly and it’s invasive,” Hooley, who wasn’t involved in the new study, told Reuters Health.

“I think (ultrasound) is actually a very, very good alternative for these patients and I would probably recommend that they just get ultrasound.”

But Dr. Susan Roth, a radiologist from the Hospital of the University of Pennsylvania in Philadelphia, said the rate of false positives with ultrasound was concerning.

“Even if you believe in screening ultrasound, the dilemma I have is the number of biopsies I’d have to do to find those cancers,” said Roth, who also wasn’t part of the research team.

Ultrasounds are time-consuming, she said, and many facilities that do cancer screening are strapped as it is. And insurance companies may not want to pay for annual ultrasounds, given how many women qualify as intermediate-risk.

“The more tests you add, we’ll find more cancers, and they’re real,” Roth told Reuters Health. “The question is, what are we willing to pay for that, in terms of the downsides and the dollars?”

Hooley pointed out that neither ultrasound nor MRI can replace annual mammography in women with higher-than-average cancer risk.

For women at normal risk of breast cancer, the government-backed U.S. Preventive Services Task Force says evidence supports mammograms only, done every other year between age 50 and 74.

Regarding the chance of false positives when other screening methods are added to the mix, Berg said women who fully understand the risks, including the need for further invasive testing, should be able to make an informed choice about what test or tests are best for them.

SOURCE: Journal of the American Medical Association, online April 3, 2012.