Abstract 3587: Identifying clinical and lifestyle factors which mediate the association between socioeconomic status and colorectal cancer mortality

Abstract Background: Higher socioeconomic status (SES) is associated with lower mortality risk for people with colorectal cancer (CRC) and contributes to geographic and racial disparities for CRC. However, the factors that mediate the association between SES and CRC mortality have not been comprehensively investigated. We performed a mediation analysis to identify clinical and lifestyle- factors that may mediate the association between household income as a proxy for SES with overall, and CRC-specific mortality in a longitudinal cohort where most participants are non-Hispanic Black with lower SES. Methods: Data arise from 1, 038 participants of the Southern Community Cohort Study (SCCS) who developed incident CRC after enrollment. Participants were aged 40-79 years at enrollment between 2002-2009; 73% self-identify as having Black racial identity. Annual household income was assessed via questionnaire at enrollment and 59% of the cohort had household income < $15, 000/year. Overall and CRC-specific mortality were determined via linkages to the National Death Index through December 31, 2020. Proportional hazards models were used to estimate hazard ratios (HRs) with 95% confidence intervals (CIs) for mortality outcomes by income level, adjusted for age, sex, and marital status. Mediation analysis was used to estimate the indirect effect of stage, healthcare-related factors (CRC screening, insurance, and surgical resection) and lifestyle-related factors (smoking status, pack years smoked, alcohol consumption, diabetes duration, diet, and physical activity) on mortality, expressed as a percentage of the association between income and mortality attributable to the mediator. Results: Income ≥ $15, 000/year was associated with lower risk for mortality, however associations were more apparent in White participants (all-cause: mortality HR 0.44, CI: 0.29-0.67; CRC-specific HR: 0.43, CI: 0.24-0.76) than Black participants (all-cause: HR 0.76, CI: 0.62-0.94; CRC-specific: HR: 0.81, CI: 0.62-1.05). Stage at diagnosis and completing surgical resection were the largest mediation factors accounting for 35% of the association between income and CRC-specific mortality among white participants and 20% of the association among Black participants. Results were similar for overall mortality. For participants identifying as Black, history of and pack-years of smoking mediated an additional 28% of the association. For White participants, smoking and the other lifestyle-related factors did not mediate the association between income and mortality outcomes. Conclusions: Higher income is associated with lower risk for mortality after CRC diagnosis. However, the factors that mediate the association may differ by self-reported race. Interventions to promote early detection of CRC and equitable access to curative surgery may help to mitigate CRC disparities related to SES. Citation Format: Shaneda Warren Andersen, Thomas Lawler, Oluwatoyosi Ogunmuyiwa, Rida A. Khatri, Mark Steinwandel, Martha Shrubsole. Identifying clinical and lifestyle factors which mediate the association between socioeconomic status and colorectal cancer mortality [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 3587.