Do False-Positive Mammograms Predict Cancer Risk?

More than half of women in the U.S. who get annual mammograms will have at least one false-positive reading after 10 years of screening, and now new research suggests that these women may be at increased risk for breast cancer.

Women in a Danish study who had at least one false-positive mammogram were more likely to eventually be diagnosed with breast cancer than women with no such history.

But there was little difference in risk among women with and without false-positive readings who were screened after the year 2000, suggesting that advances in mammography screening technology have led to more accurate testing.

"This study could be interpreted as reassuring for women being screened today," says breast cancer specialist Stephanie Bernik, MD, who was not involved with the study.

Bernik, who is chief of surgical oncology at Lenox Hill Hospital in New York City, says innovations in mammography screening since 2000 have led to better detection of breast cancer and fewer false-positives.

"There has long been a suggestion that women who have more activity in their breasts that lead to false-positive mammograms may also have an increased risk for breast cancer, but I don't think this study proves this," she tells WebMD.

False-Positive Test, More Breast Cancer

Women with positive mammography screenings - whether false or not false - typically have additional mammograms or ultrasound, followed by a biopsy to confirm or rule out breast cancer if the results are still unclear.

False-positive mammography readings are especially common in women with breasts that are dense or have other characteristics including benign growths that look like tumors, calcium deposits, skin thickening, newly retracted nipples, or suspicious lymph nodes.

False-Positives Are Common

After 10 years of annual screening, more than half of women will be called back at least once for another mammogram. And 7% to 9% will be told they should have a biopsy because of something suspicious that turns out not to be cancer, the researchers concluded.

Those false-positives may cause inconvenience and anxiety, and biopsies can cause pain and scarring, the researchers note.

They found a small but not significant increase in the chance that women diagnosed with breast cancer had a more advanced case if they underwent screening every other year instead of every year.

The study wasn't really designed to answer the question of which screening regimen is best, study researcher Rebecca Hubbard, PhD, says. Its main message, Hubbard says, is that call-backs (or recalls) for false-positive results are common, so women shouldn't panic when they occur.