The OncoSim-Breast cancer microsimulation model

Background: The increasing demand for health care resources requires measures to evaluate the impact of cancer control approaches. A cancer simulation model can help integrate new knowledge to inform clinical and policy decisions. OncoSim-Breast is a breast cancer simulation model. This paper aims to describe the key assumptions in the OncoSim-Breast model and how well it reproduces more recent breast cancer trends and the observed effects in a randomized screening trial. Methods: The OncoSim-Breast model simulates the onset, growth and spread of invasive and ductal carcinoma in situ tumours. The model combines Canadian cancer incidence, mortality, screening program and cost data to project population-level outcomes. Users can change the model input to answer specific policy questions. Here we report three validation exercises. First, we compared the model9s projected breast cancer incidence and stage distributions with the observed data in the Canadian Cancer Registry. Second, we compared OncoSim9s projected breast cancer mortality with Vital Statistics. Third, we replicated the UK Age trial to compare the model9s projections with the trial9s observed screening effects. Results: OncoSim-Breast9s projected incidence, mortality and stage distribution of breast cancer were close to the observed data in the Canadian Cancer Registry and the Vital Statistics. OncoSim-Breast also reproduced the breast cancer screening effects observed in the UK Age trial. Interpretation: OncoSim-Breast9s ability to reproduce the observed population-level breast cancer trends and the screening effects in a randomized trial increases the confidence of using its results to inform policy decisions related to early detection of breast cancer.