Figure 2 Age-adjusted actual and modelled incidence rate of invasive breast cancer, United States and Canada, 1975 to 2000 Figure 2 Age-adjusted actual and modelled incidence rate of invasive breast cancer, United States and Canada, 1975 to 2000

The age-adjusted actual and modelled incidence rates of breast cancer in the United States from 1975 to 2000 are compared with age-adjusted actual (from 1992) and modelled rates in Canada (1975 to 2000). The American model assumes screening. Two Canadian models are presented—one assuming No Screening and the other assuming screening. In both countries, the incidence of invasive breast cancer rose slowly over time, with Canadian rates consistently below those of the United States. Actual Canadian incidence appears to lies between the model prediction for No Screening and that for observed U.S. screening.

Notes: Age-adjusted to 1991 Canadian Standard Population from Surveillance, Epidemiology and End Results (SEER) data,^{Note 13} using the model for No Screening and U.S. screening patterns and from actual Canadian population incidence data. 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.