Abstract B34: Race/ethnicity and disparities in mastectomy use in the Breast Cancer Care in Chicago Study
Authors: Dookeran Keith Anthony , Silva Abigail , Rauscher Garth 
Published: May 2015

Abstract
Purpose: To examine population-based racial/ethnic disparities in mastectomy use among women with breast cancer, and explore potential predictors of this disparity.
Methods: Participants were 989 women aged 30-79 years, in a cross-sectional, population-based (NCI-funded, Breast Cancer Care in Chicago) study of newly diagnosed female breast cancer (primary in-situ/invasive) in Chicago, Illinois, from 2005-2008. Participants submitted to an in-person interview of social, health care and attitudinal factors. Medical records were abstracted for tumor characteristics and diagnostic/treatment variables. Multivariable logistic regression models with model-based-standardization were used to estimate risk differences (RDs) with bias-corrected bootstrapped 95% confidence Intervals (CIs). Models incorporated variables pertaining to various domains (socioeconomic disadvantage, cultural beliefs, health care access, and tumor aggression/progression) in order to estimate disparities in mastectomy use, and the extent to which various domains might account for the disparity.
Results: There were 397 non-Hispanic (nH) White, 411 nH Black and 181 Hispanic participants. Prevalence proportions for mastectomy use were 40% overall, 34% among nH Whites, 44% among nH Blacks, and 45% among Hispanics. Factors significantly associated with increased mastectomy use overall (p&lt; 0.05) included: younger age at diagnosis; minority ethnicity; lower socioeconomic status (SES); lack of recency of, and adherence to, screening mammography; higher tumor pathologic stage at diagnosis and higher grade; and specific self-reported beliefs/misconceptions regarding breast cancer management (notably: only need to have a lump checked if it gets bigger, mammograms can cause breast cancer, and if a breast tumor is cut open in surgery it will grow faster). In age-adjusted models, compared to nH Whites, mastectomy use was significantly increased by 10 percentage points in both nH Blacks (RD= 0.10, 95% CI: 0.02, 0.17, p= 0.006) and Hispanics (RD= 0.10, 95% CI: 0.01, 0.19, p= 0.029). In models accounting for differences in tumor stage at diagnosis and grade, the apparent disparity was reduced by about half in both nH Blacks (RD= 0.05, 95% CI: -0.03, 0.13) and Hispanics (RD= 0.04, 95% CI: -0.07, 0.13). Additional control for differences in SES, access and utilization, and beliefs/misconceptions eliminated the mastectomy disparity completely for nH Black patients (RD= -0.04, 95% CI: -0.16, 0.09) and further diminished the disparity for Hispanic patients (RD= 0.03, 95% CI: -0.10, 0.16).
Conclusions: In this population-based study, compared to nH Whites, significant disparities in mastectomy use for treatment of primary breast cancer were observed in nH Black and Hispanic women. These findings could substantially be explained by differences in tumor aggression/progression. Differences in beliefs, sociodemographics, and access variables may be contributing to disparities in mastectomy either directly or through their influence on stage at diagnosis. Our findings suggest that the best approach to reducing disparities in mastectomy would be to intervene on factors that could reduce disparities in stage at diagnosis.
Citation Format: Keith Anthony Dookeran, Abigail Silva, Garth Rauscher. Race/ethnicity and disparities in mastectomy use in the Breast Cancer Care in Chicago Study. [abstract]. In: Proceedings of the Sixth AACR Conference: The Science of Cancer Health Disparities; Dec 6–9, 2013; Atlanta, GA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2014;23(11 Suppl):Abstract nr B34. doi:10.1158/1538-7755.DISP13-B34