A JAMA report detailing the results of researchers' review of 50 years of studies of the risks and benefits of annual mammograms shows a 19% drop in deaths from breast cancer.
Whether a woman benefits from the screening depends of factors such as age and family history.
The debate over when and how often a woman should begin screening continues. Five years ago, women in the U.S. started annual testing at age 40. The U.S. Preventative Services Task Force stated later that the evidence suggests that women could wait until age 50 and get screened every other year.
Adding to the uncertainty was a long-term Canadian study that found that yearly mammograms did not reduce the chance of a woman would die of breast cancer and confirmed that many detected abnormalities would not have been fatal if left untreated.