A new randomised, follow-up trial has revealed how breast cancer screening from age 40, leads to a 25% reduction in breast cancer mortality after 10 years.
A team from the Wolfson Institute of Preventative Medicine, University of London, began recruiting women between 1990 and 1997. A total of 53,883 women were randomised to the intervention group (that is, annual screening at 40 years of age) and 106,953 to the control arm, in which mammography screening began at the currently recommended age of 50 years.
The primary outcome was mortality from breast cancer diagnosed during the trial period but before the woman’s first invitation for the usual care breast screening programme. Participants were recruited for a median of 22.8 years during which time there were 10,439 deaths, 683 (7%) of which were due to breast cancer diagnosed during the study period.
After 10 years, there were 83 breast cancer deaths in the intervention group compared to 219 in the control group with a relative risk, RR = 0.75 (95% CI 0.58-0.97, p = 0.029). However, when considering mortality beyond 10 years, there was no significant difference between the two groups. Put another way, the results suggest that screening 1150 women age 40-49 would prevent one breast cancer death.
The authors concluded that breast cancer screening from an earlier age, could potentially reduce breast cancer mortality.
Duffy SW et al. Effect of mammographic screening from age 40 years on breast cancer mortality (UK Age trial): final results of a randomised, controlled trial. Lancet Oncol 2020; August 12, 2020. https://doi.org/10.1016/ S1470-2045(20)30398-3