OncoSim-Breast cancer microsimulation model

OncoSim-Breast simulates the onset, growth, and spread of invasive tumors and ductal carcinoma in situ (DCIS) (Supplementary Figure 1). The simulation of natural history was calibrated to match Canadian cancer incidence and mortality data. The model has been described in detail earlier¹¹ and used to study the impact of breast cancer interventions on all-cause mortality.⁹ Additional details on the model and validation are provided in Supplementary Tables 1 to 4 and Supplementary Figures 2 to 5. The natural history component was inspired by the University of Wisconsin breast cancer microsimulation model.^12,13 OncoSim-Breast captures the benefits of screening on breast cancer survival using the lead time that was calibrated from observed survival data. Stage-specific outcomes were used to determine breast cancer-specific mortality. To account for geographic variation, the survival outcomes were adjusted for each province and territory using relative risks, calibrated to match province-specific cancer mortality data in the Canadian Cancer Registry. The effects of population increase and aging demographics are modeled, contributing to an annual increase in the number of breast cancers.