Adding ultrasound increased the rate of false positives fourfold. About one in 40 women who got a mammogram alone had an unnecessary biopsy, Berg said. In the group that got both a mammogram and an ultrasound, that rose to 1 in 10 women.
"That causes a lot of unnecessary stress and of course adds costs to the medical system," Berg said.
She and colleagues plan to do a cost-benefit analysis to determine whether it makes sense to add ultrasound as a routine test for high-risk women. The results are from the first year of a three-year study. In the third year, some of the women also got an advanced test known as a breast MRI.
Some studies have shown a breast MRI can detect breast cancers very early in high-risk women, but they cost $1,000 to $1,500 per test and are currently only recommended for women at extremely high risk of breast cancer. Breast MRIs also have a high rate of false positives.
"Whether in the long run ultrasound or breast MRI will be more appropriate for this purpose remains to be seen," Dr. Christiane Kuhl of the University of Bonn, Germany, wrote in a commentary.
