This funding will support the collection of the data, data management, analyses, and writing of the protocol and the technical report. [...] This evidence report will 1) seek new evidence syntheses, and assess the quality of evidence to date on the benefits and harms of screening determined by the CTFPHC as critical for decision-making, and 2) systematically review women’s willingness to be screened or uptake of screening based on how they value the benefits and harms of screening. [...] The mechanism for this is not well known, but because density reflects the proportion of epithelial and stromal tissue in the breast and breast cancer originate in the epithelial cells, the amount of density may reflect a greater number of cells that are at risk of carcinogenesis and/or an increased rate of epithelial proliferation (Boyd et al., 2005). [...] Objectives The objectives are to 1) synthesize up-to-date evidence on the benefits and harms of breast cancer screening by conducting an overview of selected systematic reviews and an updated search for more recent primary studies and to 2) systematically review how women weigh the benefits and harms of screening and how this valuation effects their decision to undergo screening. [...] The population of interest remains women aged 40 years or older who are not at high-risk for breast cancer: (a) without pre-existing or personal history of breast cancer and (b) not considered to be at risk of breast cancer on the basis of extensive family history of breast or ovarian cancer, abnormal breast pathology, deleterious genetic mutations, or previously received radiation treatment to th