Monitoring and Evaluation

The goal of breast cancer screening is a reduction in breast cancer deaths. Timely mammography screening is expected to prevent approximately one third of breast cancer deaths after 7 to 10 years from the point at which full implementation among 70% of women in the target age group is achieved^3,4. Because achieving a participation rate of 70% among women aged 50 to 69 is a gradual process, mortality rates are not immediately useful for monitoring program effectiveness. Analysis of mortality rates over time to determine the impact of screening will require a more complex research design, which takes into account the trends in screening and treatment for breast cancer. Indicators of the screening process that are valid, reliable and feasible to collect within the screening program are required to conduct interim evaluations of the impact of screening.

Interim measures used for ongoing evaluation of organized breast cancer screening programs at the national level include compliance rate, cancer detection rate, rate of advanced cancers, tumour size, and nodal status. Provincial programs also collect additional indicators that are not monitored at the national level.

Representatives of Health Canada and the breast screening evaluation community met in February 2000 as a first step towards developing a set of Canadian core indicators and targets for evaluating the performance and quality of organized breast cancer screening programs. In the meantime, provincial/territorial screening programs strive to achieve or exceed the national standards set by Sweden⁸, the Europe Against Cancer program⁹ the United Kingdom^10,11, and Australia¹² (Appendix 1).

Monitoring screening programs requires reliable, standardized information that is comparable across provinces. Some follow-up data must be obtained from external sources, thereby complicating the evaluation process. Many, but not all programs are directly linked to their provincial cancer registries to obtain cancer outcome data. Further complicating the evaluation process, some programs experience delays in obtaining registry data.

In addition, analyses have shown that breast tumour data vary from one program to another. Health Canada and the Canadian Cancer Registry are collaborating to hold a breast cancer staging training workshop in 2001 to address this issue.

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