Monday, March 3, 2014

Breast cancer screening

I hope the world will take notice of a study just published in the British Medical Journal reporting the results of a 25 year follow up randomized control trial of mammography screening. In the study, almost 90,000 Canadian women were randomized to receive either annual screening mammograms or usual care in the community between 1980 - 1985. The rates of death due to breast cancer in the two groups were indistinguishable over the study period.

The authors suggest that in a country with accessible and available treatment for breast cancer, screening mammography (as opposed to diagnostic mammography) does not improve the chances of survival with breast cancer. In addition, based on the differences in breast cancer rates between the screening and control arm, the authors report that they believe that 22% of the breast cancers diagnosed and treated in the screening arm were what they called "over-diagnosed," meaning that the diagnosed "cancer" would never have resulted in a life threatening disease.

Along with several recent articles in the past few years (like this one that described a push away from calling DCIS "cancer"), these findings suggest that the way that we are currently screening for, diagnosing, and treating breast cancer is flawed. Though it will be hard to counter the "feel good war on breast cancer" that proselytizes screening and early detection as life saving, clearly the science is speaking.

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