Adding an ultrasound to annual mammograms for women at higher-than-average breast cancer risk helps catch more early-stage tumours but increases the chance that healthy women will get follow-up biopsies unnecessarily, according to a US 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 lead author Wendie Berg, from Magee-Womens Hospital in Pittsburgh.
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,” Berg said of the study, which appeared in the Journal of the American Medical Association.
Recommendations from cancer and radiology organisations 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 that adding annual MRIs for these women 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 less expensive, 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 - also classified as intermediate risk.
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 tumours that weren't spotted on mammograms were found with ultrasound, 30 of which were invasive cancers.
Out of 612 women who opted for an 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.
Despite catching the additional cancers, 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.
“We are always in a quandary because we don't know what to do with these intermediate-risk patients,” said Regina Hooley, who studies breast cancer screening at the Yale School of Medicine but wasn't involved with the study.
“MRI is costly and it's invasive. I think (ultrasound) is actually a very, very good alternative for these patients and I would probably recommend that they just get ultrasound.”
But Susan Roth, a radiologist from the Hospital of the University of Pennsylvania in Philadelphia, said the rate of false positives with ultrasound was concerning.
“The more tests you add, we'll find more cancers, and they're real. The question is, what are we willing to pay for that, in terms of the downsides and the dollars?” she said.
For women at normal risk of breast cancer, the government-backed US Preventive Services Task Force says evidence supports mammograms only, done every other year between age 50 and 74. - Reuters