Abstract 4250: Mediation of black/white race disparity in triple-negative breast cancer by socioeconomic position, parity and p53 status

Abstract

Abstract Rauscher et al. (2016) recently suggested that the black/white race disparity in aggressive ER/PR-negative breast cancer (BC) might be transmitted through social and reproductive influences. Hence, we examined to what extent the black/white race disparity in aggressive triple-negative (TN) BC might be transmitted through social, reproductive and molecular influences. Our study sample is a previously reported historical cohort of 419 consecutively enrolled (331 non-Hispanic (nH) black and 88 nH white) women with primary BC aged 24-94 years, treated between 2000-2005 at an NCI-MBCCOP facility in Chicago, IL (Dookeran et al. 2012). US 2000 census ZIP Code Tabulation Area (ZCTA) data matched to patient address zip codes at diagnosis was used to develop a single binary measure of socioeconomic position (SEP) (> US poverty mean vs. referent of US poverty mean </= 9.2%; based on national census data for the number of families living below the poverty level threshold in 1999). Binary parity (parous vs. nulliparous) was used as a single measure of reproductive status. Binary p53 status (positive vs. negative) was used as a single indicator of molecular influence. We estimated average controlled direct associations (ACDA) using logistic regression with model-based standardization (predictive margins) in order to estimate the age/BMI-adjusted prevalence difference with bias-corrected bootstrapped 95% confidence intervals (CIs) for TN vs. luminal A type BC by race, and performed a series of ACDA (with comparison of rescaled coefficients) controlling for SEP, parity, and p53 status, both individually and together. In age/BMI adjusted models, nH black women were 15%-points more likely than nH white to have TNBC (p=0.039). This disparity was reduced to 13%-points after adjustment for p53 status, 12%-points after adjustment for parity, 11%-points after adjustment for SEP, 9%-points after adjustment for both parity and SEP (95% CI: -0.09, 0.24), and 7%-points after adjustment for p53, parity and SEP together (95% CI: -0.1, 0.79). Based on the method of rescaled coefficients, parity and SEP accounted for approximately 19% and 24% respectively of the black/white disparity in TNBC when modeled together, accounting in combination for 44% of the disparity (p=0.08). Further, p53, parity and SEP accounted for approximately 10%, 12% and 28% respectively of the race disparity in TNBC when modeled together, accounting in combination for 51% of the disparity (p=0.13). Our findings support the hypothesis that at least part of the observed black/white disparity in aggressive TNBC might be transmitted through social influences on tumor biology, in particular via SEP. Citation Format: Keith A. Dookeran. Mediation of black/white race disparity in triple-negative breast cancer by socioeconomic position, parity and p53 status [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4250.