In summary, although only mammography has been evaluated in studies that examined breast cancer mortality, what we know about the natural history of the disease suggests that supplemental screening is beneficial. Most cancers found with ultrasonography are node-negative invasive cancers, and MRI also detects some ductal carcinoma in situ. Both ultrasonography and MRI have been shown to reduce interval cancer in women with dense breasts; this is a proposed end point in the planned TMIST (Tomosynthesis Mammography Imaging Screening Trial). Magnetic resonance imaging reduces rates of late-stage and metastatic disease. I believe that supplemental screening should be available to interested women with dense breasts, but guidance to help inform the choice to have supplemental screening is sorely needed. Ideally, supplemental imaging should be performed in clinical settings that simultaneously collect data on molecular phenotypes, stage of detected cancer, other breast cancer risk factors, and outcomes of women who pursue supplemental screening. This would allow careful observational analyses comparing their outcomes to those of women with dense breasts who choose not to have supplemental tests.