Organized Breast Cancer Screening Programs in Canada - 1996 Report

Diagnostic Investigations

Screening provides only enough information to determine whether the screening visit is normal or whether further evaluation is necessary. Diagnostic tests are needed to arrive at a final diagnosis. Information on diagnostic procedures is available for 95.8% of women who had an abnormal screening visit in 1996. The remaining 4.2% were lost to follow-up or are still in the process of follow-up. Programs differ in their definition of completed follow-up: some programs report follow-up as complete before all staging information is available, and others wait for all details of the final diagnosis. Loss to follow-up can occur when a woman refuses follow-up testing, moves out of the region, or the attending physician declines to provide the follow-up information. The proportion of abnormal screens with completed follow-up differed by province (87.9% to 99.9%).

Diagnostic procedures typically involve further imaging techniques (diagnostic mammogram and/or ultrasound), fine needle aspiration, or core biopsy before surgical biopsy is resorted to.⁹ Table 7 provides information on the types of procedures received in 1996 and how these varied by province. The most common procedure performed was a diagnostic mammogram (57.3% of all procedures), followed by ultrasound (27.4%). A further 3.3% of procedures were fine needle aspirations, and 13.4% involved some type of biopsy: 10.7% were open biopsies with or without fine wire localization, and 2.7% were core biopsies.

The proportion of tests performed varied among provinces (Table 7). Reasons for these variations may include the use of clinical breast examination as a screening modality, an actual difference in the assessment process among provinces, or different methods for obtaining and recording test result information. Although data were collected on surgical consultations and physical examination by the family doctor, these figures are not presented because of inconsistent definitions and data collection procedures across provinces.

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