Health security

Majority of women diagnosed with breast cancer after screening mammograms get unnecessary treatment, study finds

More than half of breast cancers newly diagnosed in the United States are likely cases of mistaken identity that subject women to needless anxiety, treatment and expense, researchers reported Wednesday in the New England Journal of Medicine.

The study also found that the value of mammograms as a life-saving tool has been significantly overstated. Instead, the introduction of more effective treatments should get most of the credit for improving survival rates among women diagnosed with breast cancer, the researchers concluded.

The findings cast fresh doubt on the value of universal breast cancer screening for women over 40 with no family history of the disease. They also underscore that breast cancer — the most common form of cancer among American women — is a far more complex disease than initially believed.