Service screening with mammography of women aged 70-74 years in Sweden. Effects on breast cancer mortality.

Since the benefit of mammography screening for women 70 years and older is unclear, the aim of the present study was to evaluate the effect on breast cancer mortality of the population-based service-screening program in Sweden inviting women 70-74 years. Among the counties with service-screening programs in Sweden which started 1986-1990 those with upper age limit 74 years were compared to counties with 69 years as upper age limit with respect to refined breast cancer mortality. Allowance was made for potential biases namely inclusion of cases diagnosed before invitation and lead time. Two methods for estimation of breast cancer mortality were used; underlying cause of death (UCD) and excess mortality. With a mean follow-up of 10.1 years a reduction of the breast cancer excess mortality was estimated at 24%. Using the underlying cause of death the corresponding result was 6%. A non-significant reduction in breast cancer mortality was found in the counties with service-screening program including the age group 70-74 years in Sweden. The estimated reduction was larger when using excess mortality compared to the use of individual underlying cause of death.