Performance measures for the Ontario Breast Screening Program (OBSP) by age group, time period and screening modality from 10 years of breast screening were evaluated. Data were available from routine information collected on 283,962 women aged 50 to 69 screened at 73 screening centres between 1 July 1990 and 31 December 2000. Although, initially, participation in the OBSP was low, this rate increased over time and the majority of women screened returned for subsequent screening. Abnormal call rates increased slightly over the time period, were higher in women aged 50 to 59, and for women with mammographic abnormalities. Detection rates of invasive cancer were higher and prognostic features of cancers were better for women age 60 to 69, and those referred by mammography. Along with the prognostic features of cancers, the benign to malignant surgical ratio and diagnostic interval improved over the time periods and for women aged 60 to 69. Greater proportions of women had shorter diagnostic intervals and were more likely to have a diagnosis of breast cancer after surgery if they were referred by both clinical breast examination and mammography. Although some enhancements of the programme are necessary, the OBSP met or exceeded Canadian targets for most performance measures.

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Objective: To determine the association between initial screen result and returning for a second screen in an organised breast screening programme for women with a biennial screening recommendation. Setting: Women who attended the Ontario Breast Screening Program (OBSP).Methods: A retrospective cohort study was conducted of 140,723 Ontario women aged 50 years ond older who had an initial screen at the OBSP between 1 July 1990 and 31 December 1995 and were followed until 30 June 1998. Rescreening rates at 36 months and risk ratio estimates were calculated using survival methods. Age of women, year of screen, region (within Ontario) and initial screen result were compared. For initial screen results, returning for a second screen was examined by integration of screening centre with an assessment programme and by modality of referral. Results: Women with a false-positive result were less likely to return for a second screen as were women aged 70 and older and those living in regions of Ontario with fewer OBSP screening centres. However, there were minimal differences in reattendance behaviour by initial screen result for women screened at the OBSP centre with an assessment programme. Conclusions: Integration of breast screening and assessment services improved reattendance of women with false-positive screen results within an organised screening programme. I n 2001, breast cancer was diagnosed in an estimated 7200 Ontario women and an estimated 2100 women will die from the disease. I Relative survival after diagnosis of breast cancer has been improving over time in Ontario." Evidence of a reduction in breast cancer mortality rate through screening comes from the results of several randomised controlled trials and subsequent meta-analyses of these trials.':" The Canadian Task Force on the Periodic Health Examination recommends screening for breast cancer by mammography and clinical breast examination (CBE) every one to two years for women aged 50-69. 5 In Ontario most medical services are covered under the provincially managed universal health insurance plan (OHIP). Only diagnostic mammography was an insured service under ORIP prior to 1990. In 1990, the Independent Health Facilities Act allowed for the establishment and licensing of private diagnostic radiology clinics and the existing mammography billing code could also be used for screening mammograms. At the same time, the Ministry of Health established the Ontario Breast Screening Program (OBSP), under the auspices of Cancer Care Ontario to deliver an organised breast screening programme within the publicly funded health care system. In Ontario, therefore, women can receive a screening mammogram through physician or self-referral to OBSP or through physician referral to an independent radiologist.Results from randomised controlled breast screening trials have shown that a significant reduction in mortality can only be achieved after 7-10 years of regular attendance by 70% of the women in the target age group."? An understanding of how various factors are a...

Screening was able to detect a large proportion of invasive breast cancers in women with a family history, indicating their potential to benefit from regular breast cancer screening. However, due to increased interval cancer rates, screening with one-year intervals may be important even in an older population of women with a family history.