title: Mammographic density and breast cancer risk in White and African American Women.
abstract: Mammographic density is a strong risk factor for breast cancer, but limited data are available in African American (AA) women. We examined the association between mammographic density and breast cancer risk in AA and white women. Cases (n = 491) and controls (n = 528) were from the Carolina Breast Cancer Study (CBCS) who also had mammograms recorded in the Carolina Mammography Registry (CMR). Mammographic density was reported to CMR using Breast Imaging Reporting and Data System (BI-RADS) categories. Increasing mammographic density was associated with increased breast cancer risk among all women. After adjusting for potential confounders, a monotonically increasing risk of breast cancer was observed between the highest versus the lowest BI-RADS density categories [OR = 2.45, (95 % confidence interval: 0.99, 6.09)]. The association was stronger in whites, with ~40 % higher risk among those with extremely dense breasts compared to those with scattered fibroglandular densities [1.39, (0.75, 2.55)]. In AA women, the same comparison suggested lower risk [0.75, (0.30, 1.91)]. Because age, obesity, and exogenous hormones have strong associations with breast cancer risk, mammographic density, and race in the CBCS, effect measure modification by these factors was considered. Consistent with previous literature, density-associated risk was greatest among those with BMI > 30 and current hormone users (P value = 0.02 and 0.01, respectively). In the CBCS, mammographic density is associated with increased breast cancer risk, with some suggestion of effect measure modification by race, although results were not statistically significant. However, exposures such as BMI and hormone therapy may be important modifiers of this association and merit further investigation.
authors.affiliation: Department of Epidemiology, Gillings Global School of Public Health, University of North Carolina, 2104 McGavran-Greenberg, 135 Dauer Drive, Campus Box 7435, Chapel Hill, NC 27599-7435, USA. hildar@unc.edu
authors.forename: Hilda
authors.initials: H
authors.lastname: Razzaghi
authors.forename: Melissa A
authors.initials: MA
authors.lastname: Troester
authors.forename: Gretchen L
authors.initials: GL
authors.lastname: Gierach
authors.forename: Andrew F
authors.initials: AF
authors.lastname: Olshan
authors.forename: Bonnie C
authors.initials: BC
authors.lastname: Yankaskas
authors.forename: Robert C
authors.initials: RC
authors.lastname: Millikan
mesh_terms: D050154:Adiposity; D000328:Adult; D001741:Black or African American; D000368:Aged; D015992:Body Mass Index; D001940:Breast / Q000473:pathology*; D001943:Breast Neoplasms / Q000000981:diagnostic imaging* / Q000453:epidemiology* / Q000209:etiology / Q000473:pathology; D016022:Case-Control Studies; D005260:Female; D020249:Hormone Replacement Therapy / Q000009:adverse effects; D006801:Humans; D008327:Mammography; D008875:Middle Aged; D009765:Obesity / Q000150:complications; D016017:Odds Ratio; D012307:Risk Factors; D044465:White People