Metabolomic differences in young-onset versus average-onset colorectal adenocarcinoma.

Abstract

174 Background: Novel deleterious effects of environmental exposures may play a role in the rising incidence of young-onset colorectal cancer (yoCRC). We used metabolomics to assess differences between yoCRC and average-onset CRC (aoCRC), in comparison to healthy controls, which may suggest certain exposure risks. Methods: Patients with stage I-IV CRC and healthy controls were identified from prospective biobanks and categorized based on age<50 years (yoCRC or young controls) or age>60 years (aoCRC or older controls). Serum metabolites were profiled using GC-TOF mass spectrometry. Differential abundance of metabolites was investigated using unadjusted logistic regression. Metabolic pathway analysis was performed using Metaboanalyst 5.0. All p-values were adjusted for multiple testing (false-discovery rate, FDR p<0.20 considered significant). Results: The study population comprised 170 CRC patients (66 yoCRC and 104 aoCRC) and 49 healthy controls (34 young and 15 old). Association analyses revealed four differentially abundant metabolites: citrate (FDR p=0.04), cholesterol (0.14), and two unidentified metabolites (UM). Metabolic pathways significantly altered in yoCRC vs. aoCRC included: carbohydrate metabolism (citrate cycle, FDR p=0.11), carbohydrate biosynthesis (glyoxylate and dicarboxylate metabolism, FDR p=0.03), amino-acid metabolism (alanine, aspartate, and glutamate metabolism, FDR p=0.04, arginine biosynthesis, FDR p=0.04, and amino-acid t-RNA biosynthesis, FDR p=0.04). There were no significant metabolomic differences between young and older controls. Conclusions: We identified significant differences in the citrate cycle - a core pathway of cellular metabolism and associated with colorectal cancer. Metabolomic differences in pathways of carcinogenic significance (aspartate) and environmental exposures (arginine and dietary red meat) were also noted, suggesting potential relationships with younger age of CRC onset. The study provides future directions for more precise analyses with a larger sample size for healthy controls and adjusting for confounders. [Table: see text]