More than one million women have been unnecessarily treated for breast cancer that posed no harm, a new study has found.
A large study on the efficacy of mammograms found that the popular screening method has done surprisingly little to catch breast cancer before it spreads, reports CBS News.
Instead of catching late stage cancers, mammograms are too often raising a red flag for minor cases that need no treatment.
The report, published in the New England Journal of Medicine, said that up to one third of breast cancers did not need any treatment yet women were receiving unnecessary invasive procedures such as surgery, radiation therapy, hormonal therapy and chemotherapy.
"Our study raises serious questions about the value of screening mammography," wrote the researchers, led by Dr. H. Gilbert Welch of Dartmouth Medical School and Dr. Archie Bleyer of St. Charles Health System and Oregon Health & Science University.
"And although no one can say with certainty which women have cancers that are over diagnosed, there is certainty about what happens to them: they undergo surgery, radiation therapy, hormonal therapy for 5 years or more, chemotherapy, or (usually) a combination of these treatments for abnormalities that otherwise would not have caused illness."
Mammograms have been widely credited with doubling the number of cases of early-stage breast cancer that are detected each year, reports UPI, but have had little effect on the overall mortality rate for women with the disease.
The Washington Post reports that the lower rate of breast cancer deaths is due to better treatment, not early detection through mammograms.
The study will likely add more fuel to the ongoing public debate about how often women should receive mammograms.
Most health recommendations say a woman should start having annual mammograms at age 40 but study author Dr. Bleyer told CNN that women should have the screening every other year instead.
Supporters of the annual mammogram have also been weighing in on the new study.
The American Cancer Society told the Washington Post that the study “must be viewed with caution.”
The American College of Radiology charging that the study was spreading “misinformation” and “the cost may be lost lives.”