Abstract A03: Evaluating health disparities in prostate cancer: A neighborhood-wide association study (NWAS) in African Americans
Authors: Lynch Shannon M. , Handorf Elizabeth , Newcomb Craig , Zeigler-Johnson Charnita , Rebbeck Timothy R. 
Published: February 2019

Abstract
Background: African American (AA) men are more than twice as likely to be diagnosed with and die of prostate cancer (PCa) compared to White men. Risk factors from social influences to biology could be contributing to these disparities. However, empiric methods to assess the role of social or neighborhood factors in PCa are limited. In a previous study, we developed a neighborhood-wide association study (NWAS) approach, which is analogous to a genome-wide association study (GWAS), and empirically identified neighborhood characteristics from the U.S. Census associated with PCa in White men. In this study, we conducted an NWAS in AA men and preliminarily compared neighborhood and PCa effects by race.
Methods: Pennsylvania State Cancer Registry data from 1995-2005 were linked to the 2000 U.S. Census data. In a successively more stringent multiphase approach, we evaluated the association between neighborhood exposures (n = 14,663, standard deviation adjusted census variables) and prostate cancer aggressiveness (n = 911 aggressive Stage&gt;3/Gleason grade &gt;7 cases vs. n = 8632 non-aggressive Stage&lt;3/Gleason grade&lt;7 controls) in AA men. Specifically, we used generalized estimating equations in Phase 1 and Bayesian mixed effects models in Phase 2 to calculate odds ratios (OR) and credible intervals (CI), adjusting for age, year of diagnosis, spatial correlation, and multiple testing. Variables meeting statistically significant thresholds were identified and used in subsequent phases. In Phase 3, principal components analysis grouped together correlated variables, and the most significant variable within each component was identified as the study top hit.
Results: Seven variables were most significantly associated with prostate cancer aggressiveness in AA men. The top hit related to crowding in renter-occupied housing units (OR = 1.10; CI = 1.001-1.12). In White men, 17 variables were significant, and the top hit related to workers' mode of transportation (OR = 1.05; CI = 1.001-1.09). Similar to the NWAS in White men, significant associations were seen between PCa and neighborhood employment and transportation, but the specific variables used to represent these domains differed by race. Further, neighborhood education was significant in the AA analysis, but not in White men.
Conclusions: These preliminary findings suggest that associations between neighborhood circumstances and aggressive PCa may differ by race. Although further testing is needed, NWAS is a novel, empiric approach that could provide new insights into health disparities research.
Citation Format: Shannon M. Lynch, Elizabeth Handorf, Craig Newcomb, Charnita Zeigler-Johnson, Timothy R. Rebbeck. Evaluating health disparities in prostate cancer: A neighborhood-wide association study (NWAS) in African Americans [abstract]. In: Proceedings of the Tenth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2017 Sep 25-28; Atlanta, GA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2018;27(7 Suppl):Abstract nr A03.