Reproductive risk factors for breast cancer and association with novel breast density measurements among Hispanic, Black, and White women

Abstract

Purpose: There are differences in the distributions of breast cancer incidence and risk factors by race and ethnicity. Given the strong association between breast density and breast cancer, it is of interest describe racial and ethnic variation in the determinants of breast density.

Methods: We characterized racial and ethnic variation in reproductive history and several measures of breast density for Hispanic (n = 286), non-Hispanic Black (n = 255), and non-Hispanic White (n = 1694) women imaged at a single hospital. We quantified associations between reproductive factors and percent volumetric density (PVD), dense volume (DV), non-dense volume (NDV), and a novel measure of pixel intensity variation (V) using multivariable-adjusted linear regression, and tested for statistical heterogeneity by race and ethnicity.

Results: Reproductive factors most strongly associated with breast density were age at menarche, parity, and oral contraceptive use. Variation by race and ethnicity was most evident for the associations between reproductive factors and NDV (minimum p-heterogeneity:0.008) and V (minimum p-heterogeneity:0.004) and least evident for PVD (minimum p-heterogeneity:0.042) and DV (minimum p-heterogeneity:0.041).

Conclusion: Reproductive choices, particularly those related to childbearing and oral contraceptive use, may contribute to racial and ethnic variation in breast density.

Keywords: Breast density; Epidemiology; Mammography; Reproductive health.

Figure 1.

This figure depicts distributions of breast density measures by menopausal status and self-reported race and ethnicity. The (+) symbol indicates the mean. The middle line of each box shows the median. The upper and lower bounds of each box are the 75^th and 25^th percentiles, respectively. And the error bars are indicative of the upper fence (75^th percentile + 1.5*interquartile range) and lower fence (25^th percentile −1.5*interquartile range).