High breast density: What women do not know

Background: The vast majority of studies conducted since the 1990's show significant positive relationships between dense mammographic patterns and subsequent risk of breast cancer. Women with more than 75% density compared to <10% density show four to six-fold increased risk, making density a stronger risk factor than the known risk factors, other than BRCA1/2, combined. Recent studies confirm elevated risk is not an artifact of masking and suggest density after menopause is associated with aggressive tumors. Methods: A content review of the scientific and lay literature since the 1980's was conducted to assess the relationship between (1) risk factor information in both sources, and (2) density findings and screening recommendations. Results: Scientific findings were accompanied by virtually no public attention to density. Only in the late 2000's did information about risk associated with density begin to appear, but infrequently, for lay audiences. Fewer than 5% of risk factor sources reviewed included any information about breast density. Conclusion: While studies estimate sensitivity of mammography is reduced by 30% in women with very high density, the American Cancer Society does not currently recommend MRI for this group. Fourfold increased risk in the estimated 8% of the post-menopausal population with very high breast density suggests 35% of tumors are diagnosed within this group. The lack of health professional and media attention to breast density denies women the knowledge they need to advocate for identification and appropriate screening of women with high breast density.