Table 1 Selected characteristics of mammographic screening programs
From: Mammographic features associated with interval breast cancers in screening programs
Program | National Breast Screening Study (NBSS) | British Columbia (SMPBC) | Ontario (OBSP) |
|---|---|---|---|
Years of operation | 1984-90 | 1988-present | 1992-present |
Incident cancers selected for present study in years | 1984-90 | 1993-99 | 1993-98 |
Number of first examinations in selected years | 45,000 | 250,584 | 166,254 |
Recruitment | Self-referral | Letter of invitation, physician and self-referral | Physician and self-referral |
Number of centers | 15 | 19 | 8 |
Ages | 40-59 | 40-70 | 50-69 |
Frequency of screening | Annual | Annual | Every 2 years |
Physical examination | Yes | No | Yes |