Organized Breast Cancer Screening Programs in Canada

1999 and 2000 Report

Executive Summary

Breast cancer continues to be the most common cancer afflicting Canadian women, with 21,100 new cases estimated for 2003. According to 1998 estimates, breast cancer cost Canadians $1,062.8 million in terms of the value of years of life lost due to premature death. Nationally, nearly half of new cases of breast cancer occur among women aged 50 to 69. Early detection through organized breast cancer screening combined with effective treatment remains the best tool currently available to reduce breast cancer deaths among women in this age group. 

The goal of monitoring and evaluating organized breast cancer screening programs in Canada is to promote high-quality screening, ultimately leading to reductions in breast cancer mortality and morbidity, and to the minimization of the unwanted effects of screening. This document presents an evaluation of the performance of organized breast cancer screening programs in Canada for the 1999 and 2000 calendar years using newly established Canadian performance measures and targets. Data for this evaluation were submitted to the Canadian Breast Cancer Screening Database by all 10 provinces. The quality of organized screening programs is enhanced through the ongoing monitoring efforts of the Canadian Breast Cancer Screening Initiative's National Committee. 

The newly established Canadian performance measures and targets are used to monitor and evaluate organized breast cancer screening programs in Canada, ultimately leading to reductions in breast cancer mortality and morbidity.

Organized screening programs maximize the benefits to participants by detecting as many cancers as possible as early as possible. Rates of invasive cancer detection, the proportion of small invasive cancers, and the proportion of invasive cancers that have not spread to the lymph nodes reflect the extent to which programs are achieving this goal. Invasive cancer detection rates exceeded Canadian performance targets for women returning to screening, but just fell short for women at the initial screen. Performance measures indicate that screening programs were effective in finding breast cancers at an early stage, often before they could be felt or had spread to the lymph nodes. 

Performance measures indicate that programs are minimizing many of the unwanted effects of screening. Although programs missed the national targets of < 10% and < 5% for the percentage of women referred as a result of screening abnormalities, positive predictive values were within target, as were benign to malignant open biopsy ratios. Nationally, 73.3% of women not requiring surgical biopsy received a diagnosis within five weeks, and 45.6% of women requiring surgical biopsy were given a diagnosis within seven weeks. No individual program met the 90% target for timely diagnostic interval. Given that physicians outside the program setting most often coordinate follow-up, it is a challenge for programs to improve timeliness. However, remarkable progress was made in some programs, suggesting that evidence-based strategies to improve waiting times can be effective. 

To transfer the benefits of screening to the entire target population, screening programs must attempt to maximize ongoing participation. This remains a challenge. Although most programs saw increased participation in 1999 and 2000, only 30.2% of eligible women accessed organized screening nationally. The stability of participation rates is of concern, as it suggests that programs are reaching the limits of their capacity. Additional capacity exists in most provincial health care systems external to organized programs in the fee-for-service sector, where a significant number of women receive opportunistic screening. However, the performance of screening in the fee-for-service sector is not monitored or evaluated. 

In the coming years, organized screening programs will continue to provide high-quality breast cancer screening. Programs aim to achieve reductions in breast cancer mortality in the target population by conducting research to enhance the quality and effectiveness of screening, and by adapting and updating their practices as new evidence and technologies become available. The results of monitoring and evaluation efforts, such as those reported here, are used to enhance the performance of screening across Canada. 

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