Organized Breast Cancer Screening Programs in Canada - 1996 Report

Participation in Screening Programs

The number of screens in 1996 totals 310,359 among 310,036 women for all programs. As noted in Table 4, this represents a substantial increase in the number of screens from 1988, when the first province (British Columbia) began with 4,475 screens.

Despite the increase in the number of screens over the past decade, recruitment of women in the target age range continues to pose a challenge (Figure 3). Day et al⁸ state that the effect of a program on rates of breast  cancer death depends directly on the proportion of the target population that is screened. Low participation is problematic not only for program efficacy but also because women who do not participate are likely to be at a higher risk of dying from the disease. Breast screening programs in Australia and the U.K. have a minimum standard of regular attendance of 70% of women in their target age group (see Table 3).

Figure 3 Proportion of target population* who participated in provincial breast cancer screening programs in 1996

* Target population is defined as the population of women aged 50-69. Estimates were derived from Statistics Canada's Population Projections for Canada, Provinces and Territories 1993-2016. The population estimates were halved to approximate participation rates at least once every 2 years. ** Participation Rate is the number of women aged 50-69 at screening in 1996 who participated in the breast screening programs as a percentage of the target population.

None of the provincial programs achieved a 70% participation rate in 1996. Saskatchewan had the highest participation rate, with 54.2% of women in the target age group screened in that year. In contrast, Ontario had the lowest participation rate, of 10.6%. These figures, however, do not represent the complete picture of breast cancer screening in Canada. A large proportion of women in the target age group still have mammograms outside of organized breast screening programs.¹⁴ In 1994, in Saskatchewan and British Columbia, over half of all bilateral mammograms performed on women between the ages of 50 and 69 were conducted through organized breast screening programs. In other provinces, most mammography provided to women in the target age group occurred "outside" of organized screening programs.¹⁴ However, there are no systematically collected data that enable assessment of the performance of "opportunistic" screening mammography. With the expansion of provincial/territorial screening programs, the number of women participating in organized screening is expected to continue increasing.

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