Slower and smaller benefits, and more frequent adverse effects

Although there is a reasonably strong consensus that screening for breast cancer saves lives among women aged 50-69, debate is fierce about the effect in women aged 40-49. The debate is particularly strong in North America. The American Cancer Society, American Medical Association, and American College of Radiology recommend that screening should begin at age 40, while the United States Preventive Services Task Force, American College of Physicians, and Canadian Task Force on the Periodic Health Examination recommend starting at age 50. In 1993 the United States National Cancer Institute stepped back from its recommendation to begin at age 40 after reviewing the most up to date data from the seven randomised trials conducted in Edinburgh, Sweden, the United States, and Canada. The report of the institute's international workshop concluded: “For (women aged 40-49 years) it is clear that in the first five to seven years after study entry, there is no reduction in mortality from breast cancer that can be attributed to screening. There is an uncertain, and if …