WEDNESDAY, Nov. 21 (HealthDay News) -- Although mammograms have excelled at detecting breast cancer at early stages, when it can still be treated, mammography screening has failed to reduce cases of more serious late-stage disease, according to a new study.
The researchers also estimate that almost one-third of women with breast cancer are overdiagnosed via mammography -- meaning that they do not actually have cancer or they have a type of breast cancer that would not develop into potentially deadly late-stage disease.
The rate of overdiagnosis is based on data showing that the number of cases of early-stage breast cancer has grown since the mid-1980s, when mammography screening started becoming common, but that the rate of advanced disease has dropped only slightly.
"The most striking observation is that we've done nothing to really improve late-stage disease," said Dr. Archie Bleyer, chair of the Institutional Review Board at St. Charles Health System in Oregon, and lead author of the study. Late-stage disease that has spread beyond the breast area, known as distant disease, is much more lethal and is associated with only a 25 percent five-year survival rate.
The study is published in the Nov. 22 issue of the New England Journal of Medicine.
The news is not all bad: breast cancer is a less deadly disease than it was 30 years ago. According to the study, there has been a 28 percent decrease in breast cancer deaths since the mid-1970s, from 71 per 100,000 women down to 51 per 100,000.
However, Bleyer attributes that improvement to better treatments.
"All the progress we've made is due to treatment," Bleyer said. "We've been attributing it to early screening and detection, but the [steady] incidence of late-stage means we haven't really done anything to detect [deadly forms of] breast cancer earlier."
One expert believes regular mammography
All rights reserved