TABLE 3-3 Factors That Affect the Quality of Screening Mammography

Primary Source of Variation Underlying Sources of Variation
Case Variation
Breast density Breasts that are mammographically dense are associated with more false positives and false negatives42,65
  • Hormone replacement therapy generally increases breast density.
  • Menopause generally lowers breast density.
  • Overweight women usually have less dense breasts.
  • Breast density usually decreases with age.
Breast cancer history Family history of breast cancer63 Previous biopsy
Practice Variation
Individual radiologists Subspecialty training in breast imaging Volume of mammograms read (but see text) Years since training
Organization of mammography services
  • High volume centers tend to have higher accuracy, above and beyond the increase attributable to reading volume of individual radiologists
  • Number of diagnostic exams performed
  • Number of image-guided breast interventional procedures (biopsies?) performed
Double-reading of mammograms by two radiologists improves accuracy51
Use of computer-assisted detection (CAD) by nonspecialists (but see text)
Center designated as breast diagnostic and/or screening center or freestanding mammography center
Availability of prior mammograms for comparison increases specificity
Health care cystem False-positive rates have increased over time in the United States and are higher than in other countries.

From: 3, Improving Breast Cancer Screening Services

Cover of Saving Women's Lives
Saving Women's Lives: Strategies for Improving Breast Cancer Detection and Diagnosis.
Institute of Medicine (US) and National Research Council (US) Committee on New Approaches to Early Detection and Diagnosis of Breast Cancer; Joy JE, Penhoet EE, Petitti DB, editors.
Washington (DC): National Academies Press (US); 2005.
Copyright © 2005, National Academy of Sciences.

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