Abstract PR009: Gut microbiome differences across race, ethnicity, and area level deprivation among patients undergoing colorectal cancer screening in Federally Qualified Health Centers
Authors: Hogue Stephanie , Gomez Maria F. , Xu Jin , Kim Youngchul , Veramendi Rosa , Fuentes Martha , Wetzler Carolina , Burns Jessica , Forsyth Sugriva , Abdulla Rania , Meade Cathy , Gwede Clement , Byrd Doratha A. 
Published: September 2024

Abstract
Purpose: It is likely that social determinants of health influence the gut microbiome (GM). The GM is a rising risk factor for colorectal cancer (CRC), which disproportionately affects Black individuals and some Hispanic ethnic groups. We conducted a pilot investigation of the associations of race, ethnicity, and area level deprivation with the GM. Methods: We recruited adults receiving fecal immunochemical tests (FIT) for CRC screening at Federally Qualified Health Centers in a local Florida community setting. We manually extracted DNA from residual FIT stool among n=81 participants and conducted whole genome shotgun sequencing. Rarefied alpha (Observed ASVs and Shannon Index) and beta diversity (Bray Curtis distance) were calculated for species and genes. We estimated centered log ratio transformed taxonomic and functional profile relative abundances. We took an a priori approach, focused on bacteria and genes (e.g., those related to bile acids) that were previously associated with colorectal carcinogenesis. We estimated the percentage variation explained in beta diversity using multivariable PERMANOVA. Multivariable linear and zero-inflated quantile (ZINQ) regression models were used to estimate associations of race and ethnicity with microbial metrics. Results: In this pilot, n=54 (67%), n=18 (22%), and n=9 (11%) participants identified as Hispanic (H), Non-Hispanic White (NHW), and Non-Hispanic Black (NHB), respectively. The percentage variation in beta diversity explained by race/ethnicity was not statistically significant, but area level deprivation explained 3% (p=0.04) of Bray Curtis distance. Species alpha diversity was slightly lower among H individuals compared to NHW individuals (Shannon Index, β= -0.33, p=0.09). Several potentially pro-carcinogenic bacterial species and genera were more abundant among H compared to NHW individuals: Fusobacterium nucleatum (β = 0.54, pZINQ=0.01), Prevotella intermedia (β = 0.97, pZINQ=0.04), and Dialister (β = 1.69, pZINQ=0.14); Gemella morbillorum (β = 1.39, pZINQ=0.06) was more abundant in NHB compared to NHW participants. Several genes/pathways tended to be less abundant among H compared to NHW individuals, including those related to bacterial virulence [virB4 (β = -0.77, pZINQ=0.03)] and to butyrate synthesis pathways [atoB (β = -0.78, pZINQ=0.30)]. On the other hand, baiF, involved in secondary bile acid generation, was slightly more abundant among H compared to NHW participants (β = 0.23, pZINQ=0.17) while tyrB, involved in tyrosine and phenylalanine production, was slightly more abundant among NHB versus NHW individuals (β = 0.71, pZINQ=0.11). Conclusions: Several racial/ethnic differences in microbial metrics were identified. Importantly, microbiome metrics previously identified to promote colorectal carcinogenesis were more abundant in H and NHB compared to NHW individuals. Overall, our findings represent a promising first step to identifying GM-targeted intervention strategies (e.g., via diet) for effectively addressing CRC disparities.
Citation Format: Stephanie Hogue, Maria F. Gomez, Jin Xu, Youngchul Kim, Rosa Veramendi, Martha Fuentes, Carolina Wetzler, Jessica Burns, Sugriva Forsyth, Rania Abdulla, Cathy Meade, Clement Gwede, Doratha A. Byrd. Gut microbiome differences across race, ethnicity, and area level deprivation among patients undergoing colorectal cancer screening in Federally Qualified Health Centers [abstract]. In: Proceedings of the 17th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2024 Sep 21-24; Los Angeles, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2024;33(9 Suppl):Abstract nr PR009.