Effectiveness of Population-Based Service Screening with Mammography for Women Aged 70-74 Years in Sweden.

Abstract

Consensus has been reached on the effectiveness of inviting women aged 50 to 69 years to mammography screening, but for older women, the evidence is scarce. The aim of this study was to estimate the marginal effectiveness of inviting women to mammography screening with an upper age limit of 74 years versus stopping at age 69 using data from the Swedish service-screening program. A cohort design was used to compare the breast cancer mortality in the period 1986 to 2012 between geographic areas and periods where women were invited to screening up to the age of 74 years (study group) with those where women were invited up to age 69 (control group). The study group and the control group were compared using the incidence-based breast cancer mortality rate ratio where only breast cancer deaths in cases diagnosed at 70 to 74 years of age were counted. After 20 years of follow-up, there were 1,040 and 1,173 breast cancer deaths in the study and the control group, respectively. The breast cancer mortality rate ratio for women invited up to age 74 versus women invited up to age 69 was 0.80 [95% confidence interval (CI): 0.75-0.85] after bias adjustments. The corresponding rate ratio for participating women was 0.73 (95% CI: 0.66-0.81). Continuing to screen women up to 74 years of age is effective compared with stopping screening at 69 years. This large long-term study will add to the knowledge of the effect of mammography screening for women 70 to 74 years.