The number of early breast tumors detected by mammogram hasn’t led to a corresponding reduction of advanced cancer, findings that suggest increased screening has led to over diagnosis and unneeded treatment, researchers said.From The Wall Street Journal, "Study Questions Benefits of Mammogram Screening" by Melinda Beck:
Mammograms have doubled the number of early-stage breast cancers detected in the U.S. each year, while the rate of advanced disease has declined just 8 percent annually, according to a study published yesterday in the New England Journal of Medicine. One third of breast cancers detected and treated posed no threat to health, the research also found.
The study backs the 2009 guidelines by the U.S. Preventive Services Task Force that advise against routine mammograms for women ages 40 to 49 who aren’t at increased risk for breast cancer.
More than one million U.S. women have been diagnosed and treated unnecessarily for breast cancer in the 30 years since screening mammograms become widespread, according to a study in the New England Journal of Medicine.
In 2008, the most recent year studied, nearly 1 in every 3 breast cancers were "overdiagnosed"—that is, they never would have caused symptoms if they had been left alone, the study concluded.
The findings add to the growing body of evidence that suggests screening women for breast cancer leads to unnecessary treatment while saving few lives, likely fueling the controversy about when and how often to have regular mammograms.