Abstract 3731: The role of dietary patterns and microbiome composition in colorectal cancer survival: The ColoCare Study

Abstract Introduction: Diet plays a crucial role in shaping the gut microbiome, which in turn can influence cancer progression and patient outcomes. Specific dietary patterns - such as those rich in fiber, protein, and healthy fats - can promote a balanced microbiome, support immune function, reduce inflammation, and improve treatment response. In contrast, diets high in processed foods and unhealthy fats may disrupt the microbiome, potentially leading to poorer outcomes. Understanding the impact of dietary patterns on the microbiome and cancer progression could provide valuable insights into personalized nutrition strategies aimed at improving colorectal cancer (CRC) survival. This study explores the relationship between nutrient-based dietary patterns, microbiome composition, and overall survival (OS) among CRC patients. Methods: Pre-surgery fecal samples were collected from 129 stage I to IV CRC patients in the ColoCare Study, a prospective cohort of newly diagnosed CRC patients, in Utah, US and Heidelberg, Germany. To characterize the gut microbiome, we performed 16S rRNA sequencing. We calculated estimates of alpha and beta diversity, relative abundance, and a priori selected bacterial presence or absence. DESeq2 was used to quantify differential abundance. Principal component analysis was applied to identify nutrient-based dietary patterns, including 23 a priori selected macro- and micronutrients from Food Frequency Questionnaires. Nutrients were log-transformed and adjusted for total energy intake. OS was assessed in 117 stage I to III CRC patients, using multivariate Cox proportional hazards regression. Results: We identified two major dietary patterns: a “Western diet” characterized by e.g. high intake of protein, fats, and carbohydrates, and a “vitamins & minerals diet” with high intake of vitamins and minerals, especially vitamin B6, potassium, and calcium. Alpha diversity was significantly higher in stage I patients compared to stage IV (Shannon index, p=0.04) and significantly different between study centers (Shannon index, p<0.01). Beta diversity was significantly different comparing patients adhering to a low vs. high “Western diet” (Bray Curtis distance, p=0.02). We did not observe statistically significant differences in relative abundance among patients following a “Western diet” or a “vitamins & minerals diet”. Additionally, no significant association was found between microbiome composition and OS. Conclusion: While dietary patterns were linked to gut microbiome diversity, no significant association was observed between microbiome composition and OS in CRC patients. To further substantiate these findings, examining dietary patterns at the food group level may provide additional insights. Additionally, metagenomic sequencing is essential to investigate species, gene, and functional profiles in larger patient populations. Citation Format: Biljana Gigic, Tian Jin, Mmadili N. Ilozumba, Victoria Damerell, Doratha A. Byrd, Tengda Lin, Maria Gomez, Van Manh H. Le, Alireza Shamsian, Farzaneh Malekian, Jennifer Ose, Sheetal Hardikar, Jane C. Figueiredo, Christopher I. Li, David Shibata, Adetunji T. Toriola, Gianni Panagiotou, Ute Nöthlings, W Zac Stephens, June L. Round, Cornelia M. Ulrich, Caroline Himbert, Christoph Kahlert. The role of dietary patterns and microbiome composition in colorectal cancer survival: The ColoCare 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 3731.