Abstract 6206: The role of lifestyle factors in the disparities of colorectal cancer incidence: Findings from the Multiethnic Cohort Study

Introduction: Colorectal cancer (CRC) is the third most common cancer and the second leading cause of cancer death in the United States (US). In 2018, the World Cancer Research Fund/American Institute for Cancer Research (WCRF/AICR) published a score that allows the combined evaluation of adherence to their 2018 cancer prevention recommendations on diet, nutrition, and physical activity. We investigated associations between this score, and incidence of invasive colorectal adenocarcinoma across different racial and ethnic populations in the Multiethnic Cohort Study (MEC). Methods: We leveraged data collected on 204,278 Non-Hispanic Black/African American (NHB), Japanese American, Hispanic/Latine (H/L), Native Hawaiian, and Non-Hispanic White (NHW) from the MEC. The WCRF/AICR score (range 0-7) was computed at both baseline (1993-1996) and the third follow-up questionnaire (2003-2008), with higher values representing healthier lifestyle behaviors. Covariate-adjusted Cox-proportional hazards models were used to estimate the association between the WCFR/AICR score and the colorectal cancer diagnosis. Dummy variables for a 1 SD decrease or increase between the baseline and follow-up WCFR/AICR score were generated to assess trends over time in relation to CRC incidence. Results: A total of 5,993 events were reported, with 5,726 events 1 year or later after the collection of the baseline questionnaire and 1,276 a year or later after the follow-up questionnaire. Participants (55% female) had a mean age at cohort entry of 59.86 years (SD = 8.84), with a median follow-up time of 24 years (IQR = 15.31-25.74 ). The mean value of the WCRF/AICR score at baseline was 3.60 (SD = 0.89), with a significant decrease on the follow-up questionnaire (mean 3.53; SD = 0.85; paired t-test p-value <0.001). Unhealthier patterns of body mass index, fruit and vegetable, fiber, red meat and processed meat intake were reported at follow-up. We found improvements in the patterns of physical activity, sugar-sweetened drinks, and alcohol consumption. A one unit increase in the baseline WCRF/AICR score was associated with a ∼10% decrease in the risk of developing CRC (HR = 0.89; 95%CI = 0.86-0.92). When stratified by race and ethnicity, Hawaiian participants showed the greatest reduction in CRC risk (HR = 0.82; 95% CI = 0.72-0.94), followed by NHW (HR = 0.84; 95% CI = 0.78-0.90), US-born H/L (HR = 0.88; 95% CI = 0.80-0.97) and Japanese (HR = 0.90; 95% CI = 0.85-0.95) (p-heterogeneity <0.001). We saw no association was observed in NHB or non-US-born H/L. There was no evidence of differential CRC risk associated with a 1 SD change (increase or decrease) in the WCRF/AICR score between the two time points. Conclusions: Higher WCRF/AICR score values were associated with a reduced CRC risk. Moreover, the risk differs by race and ethnicity. Finally, lifestyle changes at later stages in life may not change the risk of developing CRC. Citation Format: Joel Sanchez Mendez, Jonanne Talebloo, Adelynn Paik, Sihao Han, Iona Cheng, Anna H. Wu, Ugonna Ihenacho, Lynne R. Wilkens, Loïc Le Marchand, David V. Conti, Christopher A. Haiman, Brian Z. Huang, Mariana C. Stern. The role of lifestyle factors in the disparities of colorectal cancer incidence: Findings from the Multiethnic Cohort Study [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 6206.