Plasma metabolites associated with colorectal cancer: A discovery‐replication strategy

Abstract

Colorectal cancer is known to arise from multiple tumorigenic pathways; however, the underlying mechanisms remain not completely understood. Metabolomics is becoming an increasingly popular tool in assessing biological processes. Previous metabolomics research focusing on colorectal cancer is limited by sample size and did not replicate findings in independent study populations to verify robustness of reported findings. Here, we performed a ultrahigh performance liquid chromatography‐quadrupole time‐of‐flight mass spectrometry (UHPLC‐QTOF‐MS) screening on EDTA plasma from 268 colorectal cancer patients and 353 controls using independent discovery and replication sets from two European cohorts (ColoCare Study: n = 180 patients/n = 153 controls; the Colorectal Cancer Study of Austria (CORSA) n = 88 patients/n = 200 controls), aiming to identify circulating plasma metabolites associated with colorectal cancer and to improve knowledge regarding colorectal cancer etiology. Multiple logistic regression models were used to test the association between disease state and metabolic features. Statistically significant associated features in the discovery set were taken forward and tested in the replication set to assure robustness of our findings. All models were adjusted for sex, age, BMI and smoking status and corrected for multiple testing using False Discovery Rate. Demographic and clinical data were abstracted from questionnaires and medical records.

Plasma metabolites associated with colorectal cancer stage: Findings from an international consortium

“…3 Previous studies using metabolomics have been able to differentiate between individuals with and without colorectal cancer. [4][5][6][7][8] However, few studies have investigated associations of circulating metabolites with colorectal cancer stage, and most existing studies 6,9,10 generally had relatively small sample sizes.…”

Integrating Two-Dimensional Gas and Liquid Chromatography-Mass Spectrometry for Untargeted Colorectal Cancer Metabolomics: A Proof-of-Principle Study

“…Even if a metabolite was reported in more than one study, often the direction association was different [ 23 ]. For instance, there were no lipid metabolites commonly detected in the same direction in recent studies [ 26 , 28 , 29 ]. The most consistently observed in the same direction as well as by more than one platform were pyruvic acid (up-regulated) and tryptophan (down-regulated) [ 23 ].…”

“…In addition, an increased relative abundance of malate was reported by three serum-based studies with a similar fold change to ours (×1.3) [ 21 , 32 , 36 ]. Furthermore, increased abundances of uridine and isocitrate were respectively reported in two studies [ 43 , 48 ], and four other studies found a decreased relative abundance of leucine [ 25 , 29 , 30 , 36 ].…”

“…In the past several years, a number of global metabolomic studies on CRC have been published. These studies utilized diverse biological specimens, including blood (plasma/serum) as the most common type [ 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 ], followed by tissue [ 27 , 39 , 40 , 41 , 42 ], feces [ 39 , 40 , 43 ], and urine [ 44 , 45 ], while others aimed specifically to detect volatile metabolites in breath and in other types of biospecimens [ 21 , 46 ]. To our knowledge, only two of these were prospective studies where biospecimens were collected before cancer development [ 26 , 34 ], aiming to identify etiological pathways.…”

“…Besides, as biological samples used in this study were collected after cancer treatment/resection from the cases, the direct effect of the presence of the primary tumor was deemed to have faded, although underlying metabolic deviations that fostered cancer development were expected to remain. In fact, resection of CRC does not normalize metabolic shifts seen in breath VOCs [ 68 ] or in blood total metabolites [ 29 ]. Although the storage at −80 °C is considered appropriate for most metabolomic studies, metabolite degradation over the long-term storage is certainly possible [ 33 ].…”