By Meredith Engel

It’s a medical mistake that costs taxpayers $4 billion a year – and millions of women a lot more than money.

A bombshell study found that false positive mammograms, when a healthy patient is misdiagnosed with breast cancer, happens 11% of the time, affecting 3.2 million women a year.

Over 10 years, a woman's odds of getting a false-positive result are 61%, according the report published in one health journal.

Those false positives can spur more testing and overtreatment, which jacks up costs and causes the women unnecessary distress, the authors of the study found.

"Breast cancer screening is ultimately a personal choice, which must be based on a careful consideration of the trade-off between the benefits and harms of screening," author Kenneth Mandl, a Harvard professor and physician at one Boston hospital.

Nevertheless, patients shouldn't be quick to cancel their next mammogram: the new study is based on two controversial reports that are disputed by others in the medical community, says Dr. David Dershaw, a cancer center radiologist.

"I think the author certainly had a bias and picked among published papers to find those which would support the bias," claimed Dershaw.

It’s hard to get a consensus in the medical community on the subject.