Abstract 2203: Dietary patterns and prostate cancer risk in the Multiethnic Cohort Study

Abstract Background: A growing body of research has shown the benefits of a healthy diet on a variety of cancer outcomes. Evidence is inconsistent for prostate cancer and research in diverse populations is limited. Methods: In the Multiethnic Cohort Study (MEC), we conducted a prospective cohort analysis to investigate the association of four diet quality indices (DQIs; AHEI-2010, aMED, HEI-2015, DASH; a higher score indicates healthier diet), three plant-based diet indices (PDI, hPDI, uPDI), two inflammatory (DII, EDIP), and two insulinemic dietary indices (EDIH, EDIR) (a higher score indicates more pro-inflammatory or pro-insulinemic diet) with incidence of prostate cancer (PCa) in 79, 930 men from five racial/ethnic groups (White, African American, Japanese American, Latino, and Native Hawaiian). All dietary scores were constructed from a baseline quantitative food frequency questionnaire. Outcomes examined included total PCa, high-grade PCa (Gleason score 7), advanced PCa (regional or distant), aggressive PCa (high-grade or advanced), and lethal PCa (distant or death due to PCa). Hazard ratios (HR) and 95% confidence intervals (CI) per one standard deviation (SD) increase in the dietary score were estimated from Cox proportional hazards models, overall and by race/ethnicity. Associations were considered nominally significant at P 0. 05. Results: During a mean follow-up of 18. 9 years, a total of 9, 759 incident PCa cases were identified, including 2, 503 high-grade, 1, 706 advanced, 3, 430 aggressive, and 1, 426 lethal PCa cases. None of the dietary scores was significantly associated with total PCa. We found a significant association between DII and advanced PCa (HR=1. 08, 95% CI=1. 01-1. 15) overall and the association appeared to be the strongest in African Americans (HR=1. 17, 95% CI=1. 00-1. 36) and Native Hawaiians (HR=1. 29, 95% CI=0. 98-1. 68). We also observed weak associations of the four DQIs with advanced PCa (HR of 0. 95-0. 96, P of 0. 07-0. 10) in the overall population, among which a higher DASH score was significantly associated with a 15% (95% CI = 0. 75-0. 96) lower risk of advanced PCa in African Americans. In addition, we observed that several inflammatory (EDIP) and insulinemic (EDIH, EDIR) dietary scores were associated with lower incidence of advanced, aggressive, or lethal PCa (HR=0. 89-0. 95, P of 0. 03-0. 05), which requires further investigation. Conclusions: Our findings suggest that diets with high proinflammatory potential may increase risk of advanced PCa while following a healthy dietary pattern may reduce the risk of advanced PCa. Further studies are needed to better understand the inconsistent results across studies on diet and PCa risk and whether our findings can be replicated in other populations. Citation Format: Wei Xiong, Song-Yi Park, Anqi Wang, Peggy Wan, Lynne R. Wilkens, Loïc Le Marchand, Christopher A. Haiman, Fei Chen. Dietary patterns and prostate cancer risk in the Multiethnic Cohort Study abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (6Suppl): Abstract nr 2203.