The impact of NHS breast screening on advanced disease and mortality from breast cancer in the North West of England: A cohort study

A cohort study was undertaken to describe outcomes from breast cancer in women who were aged 54 years or younger when they were first invited for NHS breast screening. The analysis included 5125 women invited for multiple rounds of breast screening by the Wigan screening programme and 10 750 women invited by the Manchester programme. The main outcome measures were rates of advanced disease and mortality from breast cancer. In Wigan 4028 (78.6%) and in Manchester 5485 (51.0%) women accepted all of their invitations for screening. The incidence of invasive cancer was higher in Wigan than in Manchester (24.78 vs 21.11 per 10 000 person-years; chi(2)=2.11, 1 df, P=0.15), but the rate of advanced disease was significantly lower (2.49 vs 4.73 per 10 000 person-years; chi(2)=4.36, 1 df, P=0.04). Mortality was lower in Wigan than in Manchester (2.46 vs 4.31 per 10 000 person-years; chi(2)=3.25, 1 df, P=0.07). In the first report of long-term outcomes in women invited for NHS breast screening, we demonstrated that it is possible to evaluate the impact of screening by comparing programmes with different proportions of regular attenders; a significant difference was shown in the rate of advanced disease between two programmes with different cancer detection and attendance rates.