Organized Breast Cancer Screening Programs in Canada

1999 and 2000 Report

The Screening Process

The process that an organized breast cancer screening program undertakes to reach its target population for screening can be described in three stages: 

• Identification and invitation of the target population 
• Provision of the screening examination 
• If an abnormality is detected, further investigation 

Women of the target age are recruited to the screening program through either a letter of invitation, a physician referral or self-referral. At the screening facility, which may be a mobile unit or a fixed site, women receive two-view mammography of each breast. In addition to mammographic screening, women attending programs in Ontario, Manitoba, Nova Scotia, Prince Edward Island, and Newfoundland and Labrador receive a clinical breast examination (CBE) performed by a trained health professional; the remaining programs encourage women to obtain regular CBE outside the program from their family physicians (Table 1). 

All programs provide screening results to both the woman and her physician. If the screening result is normal, women who are still eligible will be recalled by letter of invitation for another routine screen. This generally occurs after two years, although a minority of women are recalled annually on the basis of age, mammographic results, family history, or other factors that vary across programs. Women with an abnormal screening result are informed, along with their family physician, of the need for further assessment. Depending on the program, diagnostic follow-up is coordinated either by the woman's physician or through an integrated process directed by the screening program. Diagnosis is complete when a final diagnosis of either cancer or normal/benign is reached. Figure 2 illustrates the pathway in more detail. 

Program participants are advised that, although mammography is highly effective in the early detection of breast cancers, there is a possibility that some cancers are undetectable by mammography. A small number of women may develop symptoms in the interval before their next screening visit and are encouraged to consult their physician as soon as symptoms are found. 

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