Figure 1 Age-specific incidence rate of invasive breast cancer from Surveillance, Epidemiology and End Results (SEER) Program (1990) and Statistics Canada (1992), by age and modelled rate in absence of screening (1990), by selected birth cohort Figure 1 Age-specific incidence rate of invasive breast cancer from Surveillance, Epidemiology and End Results (SEER) Program (1990) and Statistics Canada (1992), by age and modelled rate in absence of screening (1990), by selected birth cohort

The age-specific incidence rate of invasive breast cancer in the United States in 1990 is compared with the rate in Canada in 1992. In both countries, rates rose steadily from about 50 per 100,000 at age 40 to more than 400 per 100,000 by age 70. Rates in the United States consistently exceeded those in Canada. Modelled rates for Canada indicate that in 1990, in the absence of mammography screening, the rate for the 1920 birth cohort would be more than 350 per 100,000 for the 1920 birth cohort, about 300 per 100,000 for the 1930 birth cohort, about 200 per 100,000 for the 1940 birth cohort, and just over 100 per 100,000 for the 1950 birth cohort.

Note: The cancer onset rate in the model was decreased by 15% from that used in U.S. studies to better reflect Canadian incidence rates.^{Note 10}

Sources: Surveillance, Epidemiology and End Results Program; Canadian Cancer Registry; University of Wisconsin Breast Cancer Epidemiology Simulation Model; Canadianized University of Wisconsin Breast Cancer Epidemiology Simulation Model.