We know that routine breast cancer screening is beneficial in women aged 50-70, but the effects in slightly younger and older women is still uncertain. In response to this, the AgeX trial was established in 2010 offering additional screening to women aged 47-49 and 71-73. Randomisation is by means of clusters to include women invited for screening with their counterparts who are not invited for screening at 65 of the 80 breast cancer screening centres in England.
Follow-up is by flagging for death and cancer incidence and linkage to hospital discharge data in England.
By the end of 2016, 3m women have been randomised with a total of 1m screened already making the AgeX trial one of the largest randomised trials in medicine. Recruitment continues until 2020.