Breast cancer screening and overdiagnosis

Overdiagnosis is a harmful consequence of screening which particularly challenging to estimate. An unbiased setting measure overdiagnosis in breast cancer requires comparative data from screened and an unscreened cohort for at least 30 years. Such randomised will not become available, leaving us with observational over shorter time periods outcomes modelling. This collaborative effort the International Cancer Screening Network quantified variation estimated organised programmes evaluation both observed simulated data, presented examples how modelling can provide additional insights. Reliable analysed study design accounting methodological pitfalls, studies different approaches, indicate that accounts less than 10% invasive cases target population women aged 50 69. Estimates above this level are likely derive inaccuracies design. The widely discrepant estimates reported could substantially be reduced by use 10 years follow-up after stops. In contexts where concomitant opportunistic or gradual implementation occurs, on valid comparison groups readily intervention becomes advantageous option obtain reliable overdiagnosis.