title: The Potential Impact of Risk-Based Screening Mammography in Women 40-49 Years Old.
abstract: OBJECTIVE
  The purpose of this study was to determine the prevalence of very strong family history and extremely dense tissue in women 40-49 years old with breast cancer detected on screening mammography.
  
  
  METHODS
  All cancers detected by screening mammography at our institution between January 1997 and November 2012 in 40- to 49-year-old women were retrospectively identified. Those with a personal history of breast cancer were excluded. Family history, breast density, type of malignancy, hormone receptor status, and lymph node status were recorded.
  
  
  RESULTS
  One hundred thirty-six cases of breast cancer were identified on screening mammography in 40- to 49-year-old women; 50% were invasive cancers, and 50%, ductal carcinoma in situ. Very strong family history was absent in 88%, and extremely dense breast tissue was absent in 86%. Seventy-six percent of patients had neither very strong family history nor extremely dense breasts, including 79% of the cases of invasive cancers, of which 25% had axillary nodal involvement and 89% were estrogen receptor positive.
  
  
  CONCLUSIONS
  Very strong family history and extremely dense breast tissue were absent in most 40- to 49-year-old women with breast cancer detected at screening mammography. These cancers were frequently invasive (often with nodal metastases) and treatable (hormone receptor positive). Reducing the number of women to be screened in this age group by using this risk-based approach would reduce the number of screen-detected cancers by more than 75%, thereby precluding the benefit of mortality reduction. Even using a risk-based strategy with an expanded definition of high risk that included any first-degree family history, extremely dense tissue, or both, 66% of malignancies would still be missed.
authors.affiliation: 1 Department of Radiology and Biomedical Imaging, University of California San Francisco, 1600 Divisadero St, Rm C-250, San Francisco, CA 94115.
authors.forename: Elissa R
authors.initials: ER
authors.lastname: Price
authors.affiliation: 2 Department of Radiology, Kaiser Permanente Medical Center, South San Francisco, CA.
authors.forename: Alexander W
authors.initials: AW
authors.lastname: Keedy
authors.affiliation: 3 City of Hope National Medical Center, Duarte, CA.
authors.forename: Rita
authors.initials: R
authors.lastname: Gidwaney
authors.affiliation: 1 Department of Radiology and Biomedical Imaging, University of California San Francisco, 1600 Divisadero St, Rm C-250, San Francisco, CA 94115.
authors.forename: Edward A
authors.initials: EA
authors.lastname: Sickles
authors.affiliation: 1 Department of Radiology and Biomedical Imaging, University of California San Francisco, 1600 Divisadero St, Rm C-250, San Francisco, CA 94115.
authors.forename: Bonnie N
authors.initials: BN
authors.lastname: Joe
mesh_terms: D000328:Adult; D001943:Breast Neoplasms / Q000000981:diagnostic imaging* / Q000235:genetics; D002285:Carcinoma, Intraductal, Noninfiltrating / Q000000981:diagnostic imaging* / Q000235:genetics; D055088:Early Detection of Cancer; D005260:Female; D006801:Humans; D008207:Lymphatic Metastasis; D008327:Mammography; D008875:Middle Aged; D009361:Neoplasm Invasiveness / Q000000981:diagnostic imaging; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors
keywords: breast cancer; breast density; family history; risk-based screening