Canadian Study on Mammography

A study by Miller et al published in the British Medical Journal on February 11, 2014 found that annual mammograms do not lower the risk of women dying of breast cancer and questions the value of mammography.  Their study stirs anew the debate if women should have mammograms at all and its suggestions are diametrically opposite of the current recommendations by the American Cancer Society and the American College of Radiology that women should have annual mammograms between the ages 40 and 70.   

In their prospective, randomized study they followed 89,835 women over a period of 25 years.  Women aged 40-49 in the mammography arm and all women aged 50-59 in both arms received annual physical breast examinations. Women aged 40-49 in the control arm received a single examination followed by usual care in the community.  During the five-year screening period, 666 invasive breast cancers were diagnosed in the mammography arm (n=44 925 participants) and 524 in the controls (n=44 910), and of these, 180 women in the mammography arm and 171 women in the control arm died of breast cancer during the 25-year follow-up period.  They also found a 22% over-diagnosis. 

They concluded that annual mammography in women aged 40-59 does not reduce mortality from breast cancer beyond that of physical examination or usual care when adjuvant therapy for breast cancer is freely available.