6th International Workshop on Breast Densitometry and Breast ...

6 th <strong>International</strong> <strong>Workshop</strong> on Breast Densitometry
and Breast Cancer Risk Assessment
BENIGN BREAST DISEASE, MAMMOGRAPHIC BREAST DENSITY AND THE RISK OF
BREAST CANCER
Jeffrey A. Tice, MD; Ellen S. O’Meara, PhD; Donald L. Weaver, MD; Celine Vachon, PhD; Rachel
Ballard-Barbash, MD, MPH; Karla Kerlikowske, MD
ABSTRACTS FOR SPEAKERS
Division of General Internal Medicine, Department of Medicine; General Internal Medicine Section,
Department of Veteran Affairs and Departments of Medicine and Epidemiology and Biostatistics (Drs.
Kerlikowske); University of California, San Francisco, San Francisco, CA. Group Health Research
Institute (Dr. O’Meara); Department of Pathology, University of Vermont College of Medicine and
Vermont Cancer Center (Dr. Weaver). Applied Research Program, Division of Cancer Control and
Population Sciences, National Cancer Institute (Dr. Ballard-Barbash).
Background: Benign breast disease and high breast density are prevalent, strong risk factors for breast
cancer. Women with both risk factors may be at very high risk.
Methods: We included 42,818 women participating in the Breast Cancer Surveillance Consortium
(BCSC) from 1994 through 2009 who had no prior diagnosis of breast cancer and had undergone at least
one benign breast biopsy and mammogram; 1,359 women developed incident breast cancer in 6.1 years of
follow-up (78% invasive, 22% DCIS). Community radiologists rated breast density using Breast Imaging
Reporting and Data System categories: almost entirely fat (low density); scattered fibroglandular densities
(average density); heterogeneously dense (high density); extremely dense (very high density).
Results: In Cox regression models, benign breast disease and breast density were independently
associated with breast cancer. Atypical hyperplasia and very high density was uncommon (0.6% of
biopsies), but associated with the highest risk [hazard ratio (HR); 5.3, 95% confidence interval (CI) 3.5-
8.1] compared to non-proliferative changes and average density. Proliferative disease without atypia (26%
of biopsies) was associated with elevated risk that varied little across levels of density: average (HR 1.4,
95% CI 1.1-1.7), high (HR 2.0, 95% CI 1.7-2.4), or very high (HR 2.0, 95% CI 1.5-2.7). Low breast
density (4.5% of biopsies) was associated with low risk (HRs