Background
False-positive recall is a recognised disadvantage of mammographic breast screening and the rate of such recalls may be higher in younger women, potentially limiting the value of screening below age 50.
Methods
Attendance and screening outcome data for 53 884 women in the intervention arm of the UK Age trial were analysed to report observed false-positive recall rates during 13 years of trial fieldwork. The Age trial was a randomised controlled trial of the effect of mammographic screening from age 40 on breast cancer mortality, conducted in 23 NHS Screening centres between 1991 and 2004. Women randomised to the intervention arm were offered annual invitation to mammography from age 40/41 to age 48.
Results
Overall, 7893 women (14.6% of women the intervention arm and 18.1% of women attending at least one routine screen) experienced one or more false-positive screen during the trial. The rates of false-positive mammography at first and subsequent routine screens were 4.9% and 3.2%, respectively. The cumulative false-positive rate over seven screens was 20.5%. Eighty-nine percent of women who had a false-positive recall at their previous screen attended their next invitation to routine screening.
Conclusions
Rates of false-positive recall in the Age trial were comparable with the national screening programme, however, the positive predictive value of referral was lower. Experiencing a false-positive screen did not appear to lessen the likelihood of re-attendance in the trial.
Impact
The question of greatly increased false-positive rates in this age group and of their compromising re-attendance is refuted by the findings of this study.