Ten years of breast screening in the Screening Mammography Program of British Columbia, 1988–97

Objectives To evaluate 10 year outcomes of the Screening Mammography Program of British Columbia (SMPBC) and determine if breast screening targets were being achieved among women aged 40–80+ years.Setting Organised breast screening programme in British Columbia, Canada.Methods Rates of participation, abnormal referral, cancer detection, and interval cancer were calculated for asymptomatic women receiving an SMPBC mammography from 1988–97.Results 895 849 screening mammographies were provided to 335 433 women. 51.3% of women were age 50–69 years. Abnormalities were identified on 57 454 screens (6.4%) from which 3304 cancers were detected. Abnormal call rates were higher on first (9.8%), compared with subsequent screens (4.4%) and declined with age: 7.7% at age < 40 to 5.4% for age 70–79 years. Cancer detection rates were higher on first (5.0 per 1000) compared with subsequent screens (2.8 per 1000) and increased smoothly with age from 1.4 to 8.2 per 1000 from age < 40 to age 80 years and older. Twenty per c...