Effectiveness of population-based service screening with mammography for women ages 40 to 49 years: Evaluation of the Swedish Mammography Screening in Young Women (SCRY) Cohort

摘要

In a recent study, Hellquist et al. estimated the mortality reduction attributable to mammographic screening among Swedish women aged 40-49 years to be 29% (95% confidence interval [CI], 20%-38%). The study is of high quality, and is a landmark study on an important topic. However, we suggest another way of calculating the estimated mortality reduction that would reduce the estimated screening effect on breast cancer mortality somewhat. Hellquist et al. divided Swedish counties into those that have or have not introduced screening for women 40-49 years of age. They first tested for any statistically significant prescreening differences in mortality between the later screening and nonscreening counties, concluding that there were no differences in mortality.