Abstract 4181: Geospatial heterogeneity in colorectal cancer screening among Hispanic subgroups
Authors: Buchalter Robert Blake , Rose Johnie , Stern Mariana C. , Figueiredo Jane C. , Schmit Stephanie L. 
Published: April 2023

Abstract
The U.S. Hispanic population has significantly lower colorectal cancer (CRC) screening rates than any other racial/ethnic group, resulting in unchanged incidence and mortality rates over recent decades. Recent studies have identified geographic variation in Hispanic CRC screening rates, but little is known about patterns among Hispanic subgroups. Here, we examine statistical and geographic relationships between broadly defined racial groups, Hispanic subgroups, and nationwide CRC screening rates. USPSTF guideline-adherent CRC screening rates for census tracts were obtained from 2018 CDC Places. Tract race/ethnicity %s, including non-Hispanic White (NHW), non-Hispanic Black (NHB), Asian, and Hispanic subgroups (Mexican, Cuban, Puerto Rican (PR), Dominican, Central/South American (CSAm), and other Hispanic), female %, and area deprivation index (ADI) were obtained from 2015-2019 American Community Survey 5-year estimates. Race/ethnicity %s were transformed using additive log ratios to account for the compositional nature of racial categories. A linear model and geographically weighted regression (GWR) were fit with CRC screening rate as the outcome. The mean CRC screening rate for 72,117 U.S. census tracts (99% of tracts) was 63.7% (SD=7.0). Linear modeling (R2=0.68) showed significant positive linear associations between CRC screening and female % (p&lt0.001), NHW % (p&lt0.001), NHB % (p&lt0.001), and Asian % (p=0.002), and significant negative associations between screening and ADI (p&lt0.001) and all Hispanic subgroups (p&lt0.001). Mexican, Cuban, PR, Dominican, and CSAm subgroups had significant screening rate drops of -1.48%, -0.26%, -0.15%, -0.30%, and -0.52%, respectively, per 1 unit increase in subgroup %. ADI had strong effects on all screening-race associations, with a flip in directionality for NHB% (negative to positive) and weakening of slopes for all other racial categories after adding ADI in the final adjusted model. GWR results (R2=0.94) displayed spatial heterogeneity in local coefficients of all predictor variables, with distinct regional patterns in relationships between screening and ADI (strongly negative local coefficients in OH and OK), Mexican % (strongly negative in TX, AZ, NV, and CA), and NHB % (strongly negative in FL, GA, MS and WI; positive in SC and NC). This work suggests Mexican, CSAm, and Dominican subpopulations may be driving the low CRC screening rates among Hispanics overall. Local variability suggested the importance of where subpopulations live in determining guideline-concordant screening. ADI strongly altered screening-race relationships, with directionality changing for NHB %, further displaying the importance of area deprivation in CRC screening. Future work should explore micro-level drivers of spatial heterogeneity in screening rates across both broadly defined racial groups and Hispanic subgroups in the U.S.
Citation Format: Robert Blake Buchalter, Johnie Rose, Mariana C. Stern, Jane C. Figueiredo, Stephanie L. Schmit. Geospatial heterogeneity in colorectal cancer screening among Hispanic subgroups. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4181.