The Impact of Breast Cancer Screening on Population Health

textabstractBreast cancer is an important public health problem with an estimated number of 1.38 million breast cancer cases and 458,000 deaths from the disease yearly worldwide. Randomized trials have shown that mammography screening significantly reduces breast cancer mortality. Besides the benefits in terms of lives saved, mammography screening is, however, also associated with harms, such as false-positive test results and overdiagnosis. This thesis describes the impact of breast cancer screening in the population and compares the effects to the effects of other interventions. We found that mammography screening has had a substantial impact on breast cancer mortality in the U.S. and is projected to continue to do so in the future. Screening women biennially from age 50 to 74 years leads to a favorable balance between benefits and harms. More intensive screening (either extending the age ranges or increasing the screening frequency) leads to more benefits (lives saved), but harms increase more steeply. Targeting screening to subgroups with the highest chance for benefit and the lowest chance for harm has the potential to improve the balance between benefits and harms at the population level