1 From the Section for Mammographic Screening, Cancer Registry of Norway, PO Box 5313, Majorstuen, Oslo 0304, Norway (S.H.); Department of Health and Care Sciences, UiT-The Arctic University of Norway, Tromsø, Norway (S.H.); Department of Radiology, University of Washington School of Medicine, Seattle, Wash (C.I.L.); and Department of Health Systems and Population Health, University of Washington School of Public Health, Seattle, Wash (C.I.L.).