Trends in diagnostic confirmation and treatment of pre-malignant abnormalities at screening mammography

Thanks to national breast cancer screening, breast abnormalities can already be detected before they cause symptoms. The earlier breast cancer or possible pre-stages are detected, the better the prognosis for the woman. In addition to breast cancer, screening also detects abnormalities that are not breast cancer or are only a pre-stage (DCIS), which can sometimes, but not always, develop into breast cancer. This thesis provides important new insights into the usefulness of national breast cancer screening: by filtering out high-grade DCIS in particular, less high-grade/more aggressive breast cancer can be found through screening. On the other hand, improved digital screening techniques have also led to an increase in diagnosing breast abnormalities of which the biological behaviour remains mostly - but not always - benign (premalignant abnormalities). Diagnosing and treating these abnormalities leads to overtreatment, which is an unintended but unavoidable consequence of screening. This dissertation also describes the trends in referral, additional studies and treatment of these premalignant abnormalities.