Abstract 3576: Socio-environmental exposure leads to disparities in colorectal cancer mortality and tumor biology in metropolitan Detroit

Abstract Non-Hispanic Black (NHB) patients face the highest colorectal cancer (CRC) mortality rates in the US, heavily influenced by social determinants of health (SDOH). Neighborhood quality, a key SDOH, impacts both socioeconomic factors and exposure to cancer-related environmental contaminants which has direct implications in tumor biology. Thus, in studying the role of environmental justice on health outcomes it is crucial to account for the separate and combinatory effects of environmental and socioeconomic burden. We expect socio-environmental exposures to increase the risk of CRC mortality among NHB patients, as well as alter tumor biology among those with the highest exposure. We utilized the Centers for Disease Control and Prevention’s (CDC) comprehensive socio-environmental variable available at the census tract level called the Environmental Justice Index (EJI) to first compare social vulnerability (SVM), environmental burden (EBM), and their combined Social Environmental Score (SER) to the risk of CRC mortality by race. Patient data including census tract at diagnosis, demographics, and clinical features were obtained from the Metropolitan Detroit Cancer Surveillance System population-based cancer registry for 9727 Non-Hispanic White (NHW) and 3778 NHB invasive CRC cases. EJI variables were converted to quartile-level variables, and mortality risk was evaluated for quartile 4 (highest burden) compared to quartile 1 (lowest burden). Associations were tested via Cox Proportional Hazards regression. In nearly all models, EJI variables increased the risk of mortality. SVM showed stronger effects overall compared to EBM, and most models showed similar effects among race and age groups in both overall and cancer-specific mortality. A notable exception to this was that NHB early onset (EO) patients showed an elevated risk of cancer-specific mortality due to EBM (HR=1.98, 95% Confidence Interval (CI)=1.20-3.26, p=0.0071) compared to SVM (HR = 1.10, 95% CI = 0.61-2.00, p=0.75), and also compared to NHW EO EBM (HR=1.40, 95% CI=0.88-2.25, p=0.16) and NHW EO SVM (HR=2.12, 95% CI = 0.97-4.61, p=0.059). Additionally, we have noted that NHB patients are more likely to have KRAS mutations than BRAF, and comparative analyses are underway to compare molecular subtypes to exposure level. Our results suggest that environmental burden may play a role in racial disparities by age, and further analyses investigating the molecular implications of these exposures are needed to better understand the molecular mechanisms driving tumor progression and mortality disparities. Citation Format: Natalie Gail Snider, R Blake Buchalter, Theresa Hastert, Gregory Dyson, Carina Gronlund, Elena Stoffel, Laura Rozek, Ann Schwartz, Kristen Purrington. Socio-environmental exposure leads to disparities in colorectal cancer mortality and tumor biology in metropolitan Detroit [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 3576.