Overdiagnosis on breast cancer screening
The benefit of breast cancer screening has been demostrated since 1960, but the growing concern about the harms of mammography screening was noticed, in particular the problem of overdiagnosis which occurs when screening detects a breast cancer that would not have presented clinically in the women's lifetime in the absence of screening. Overdiagnosis results in unnecessary biopsies, overtreatment and also the psycho-social consequences but it is impossible to identify which tumors are overdignosed. Although the overdiagnosis cases can not be distinguished in the individual level, the phenomenon in the population level can be evaluated. However, qauntifying the overdiagnosis is difficult, especially in the service screening. That is because of in the absence of a control group and the increasing incidence uncertainly over time. Estimates of overdiagnosis in the previous studies range from less than 1% to 54%. The discrepancy can probably explained by methodological difficults. Since the National Board of Health and Welfare in Sweden issued screening guidelines in 1986, the service screening have been launched. The aim of our study is to estimate the overdiagnosis in Västernorrland, Västerbotten, Norrbotten and Stockholm through applying different estimation methods such as cumulative incidence approach, incidence rate approach, multi-state model and micro-simulation approach. We plan to do a serious of simulations to check the robustness of the methods.