Mammograms do reduce mortality from breast cancer, according to an evaluation by a working group convened by the International Agency for Research on Cancer of the World Health Organization.
Dr. David Thomas of the Public Health Sciences Division was among 24 experts from 11 countries who constituted the working group.
The consensus on the value of mammography screening recently was challenged by Danish investigators who argued that many studies were scientifically flawed and concluded that there was no overall benefit from mammography.
The working group met in Lyon, France, last month to evaluate results published from multiple mammography screening studies. It concluded that trials have provided sufficient evidence for the efficacy of mammography screening of women 50 to 69. The reduction in mortality from breast cancer for those in this age group who chose to participate in screening was estimated at 35 percent.
For women 40 to 49, the group found only limited evidence for a reduction. The working group found that many earlier criticisms of mammography were unsubstantiated, and the remaining deficiencies were judged not to invalidate the trials' findings.
One million women develop breast cancer each year worldwide. Early detection and treatment are considered the best approach to reduce breast-cancer mortality.
The first screening trial of mammography was initiated in 1963. Since then, studies have been carried out in different countries. Most have reported reductions in breast cancer mortality and several countries have now established breast cancer screening programs.
The effectiveness of national screening programs varies due to differences in coverage of the female population, quality of mammography, treatment and other factors. Organized screening programs are more effective in reducing the rate of death from breast cancer than sporadic screening of selected groups of women.