Neighborhood Deprivation and DNA Methylation and Expression of Cancer Genes in Breast Tumors

Abstract

Importance: The biological processes that underlie the association of neighborhood environment with chronic diseases, such as cancer, remain poorly understood. Objective: To determine whether differences in breast tissue DNA methylation are associated with neighborhood deprivation among Black and White women with breast cancer. Design, Setting, and Participants: This cross-sectional study collected breast tissue from women undergoing surgery for breast cancer between January 1, 1993, and December 31, 2003. Participants were recruited through the University of Maryland Medical Center, with additional collection sites at Baltimore-area hospitals. Data analysis was performed from March 1 through December 1, 2022. Exposure: Year 2000 census tract-level socioeconomic deprivation measured via neighborhood deprivation index (NDI) as a standardized score, with Black and White race being ascertained through self-report. Main Outcome and Measures: The primary outcome was tissue DNA methylation using genome-wide measurements. The secondary outcome was tissue gene expression. Results: Participants included 185 women with breast cancer (110 Black [59.5%], 75 White [40.5%]). Mean (SD) age at surgery was 56.0 (14.1) years. Neighborhood deprivation was higher for Black women than for White women (Mean [SD] NDI, 2.96 [3.03] for Black women and -0.54 [1.91] for White women; difference, -3.50; 95% CI, -4.22 to -2.79; P