Women who have hesitated over mammograms because of the risk of overdiagnosis now have new evidence to consider. A reanalysis of the major randomized mammography trials, published in the Journal of the National Cancer Institute on Sept. 14, found results consistent with overdiagnosis below 5%. Some past estimates drawn from the same trials ran as high as 30% to 50%.
Overdiagnosis happens when screening finds a cancer that would never have caused symptoms or threatened a woman's life. Because doctors cannot tell which tumors those are, overdiagnosed women still go through surgery, radiation, or hormone therapy. That possibility has been one of the main reasons some women delay or skip screening.
