Top Line: What is the optimal age to begin routine breast cancer screening with mammography?
The Study: Now there’s a highly debated topic. The data is fairly clear that beginning mammography at age 40 results in reduced breast cancer mortality. The debate is over whether this benefit outweighs the risks of over-diagnosis. The UK Age trial is one of the huge randomized trials that helps inform this discussion. While it has been reported before, it’s always good to have a refresher with updated long-term results (23 years to be exact). In UK Age, nearly 170,000 women aged 39-41 were randomized to routine screening starting at age 50 or early screening every year at age 40 continuing on to routine screening after 50. The question was whether early screening would reduce the risk of breast cancer mortality (BCM) in the time prior to everyone starting routine screening. In other words, a woman had to be diagnosed with and die from a breast cancer in her 40’s to be counted as an event. Prior results had shown that during the intervention period, there was a significant reduction in BCM during the first 10 years that was attenuated after everyone started routine screening. The important finding in this long-term follow-up was that the absolute reduction in BCM persisted over time, suggesting the BCM benefit during the first 10 years was from actual lives saved and not just postponement of events until after 10 years.
TBL: After 20+ years of follow-up, UK Age demonstrates beginning breast cancer screening at age 40 prevents (rather than postpones) breast cancer mortality without adding to the baseline risk of over-diagnosis. | Duffy, Lancet Oncol 2020