Figure 1.

Discrete-event simulation model. All simulated women start in a breast cancer-free stage and may move progressively through local, regional, and distant stages of breast cancer and death due to breast cancer. In each cycle they may also remain in their current stage. The progression between local, regional, and distant stages is conditional on a simulated woman’s natural history of BC, her propensity for compliance, and her tumor growth rate. Under the clinical detection arm, clinical detection may occur in the breast cancer stage to which a simulated woman has progressed. These are clinically detected local, regional, and distant stages. Correspondingly, under the screen detection arm, breast cancer may be detected via mammography or MRI in local, regional, or distant stages. At all stages, simulated women are also susceptible to death from all other nonbreast cancer causes. BC death = death due to breast cancer; BCF = breast cancer free; CDD = clinically detected breast cancer, distant stage; CDL = clinically detected breast cancer, local stage; CDR = clinically detected breast cancer, regional stage; SDD = screen-detected breast cancer, distant stage; SDL = screen-detected breast cancer, local stage; SDR = screen-detected breast cancer, regional stage.