# Metabolic Signature in Combination with Fecal Immunochemical Test as a Non-Invasive Tool for Advanced Colorectal Neoplasia Diagnosis

## TL;DR

This study identifies cholesteryl esters in fecal samples as potential biomarkers to improve early diagnosis of colorectal cancer when combined with existing tests.

## Contribution

The study introduces cholesteryl esters as novel biomarkers to enhance the accuracy of colorectal cancer diagnosis when combined with fecal immunochemical tests.

## Key findings

- Cholesteryl esters and fecal hemoglobin clearly differentiate CRC from healthy and adenoma groups.
- Combining cholesteryl esters with FIT improves CRC diagnosis accuracy but not adenoma detection.
- Adenoma is a heterogeneous transitional stage with unclear metabolic patterns compared to CRC.

## Abstract

Screening programs have decreased the incidence rates of colorectal cancer (CRC), but more efforts are needed for an early diagnosis. For this purpose, we perform a metabolomics analysis in fecal sample from three groups of patients: healthy individuals (CTRL), adenocarcinoma (AA) and CRC. In this study, groups CTRL and AA, as well as CTRL and CRC, are clearly separated and the results obtained allow us to enhance the accuracy of CRC diagnosis by adding cholesteryl esters (CEs) as biomarkers to the current diagnosis tool fecal immunochemical test (FIT). In addition, our results support the study of cancer metabolism using LC-MS-based metabolomics for the identification of sensitive and accurate biomarkers and potential therapeutic targets.

Background/Objectives: Colorectal cancer (CRC) is one of the most prevalent cancers worldwide. Even though the screening programs have decreased the incidence rates, the prognosis for CRC varies depending on the stage at diagnosis. Thus, early diagnosis is still a big challenge due to screening methods, and subsequent diagnosis is not very sensitive. Methods: In this work, LC-MS-based metabolomics, a powerful and sensitive tool to study complex dynamic changes, was used to analyze 211 human fecal samples from control individuals (CTRL), adenoma (AA), and CRC patients. Results: Multivariate and univariate statistical analysis highlighted cholesteryl esters (CEs) and fecal haemoglobin, quantified by fecal immunochemical test (FIT), as relevant biomarkers that clearly differentiate CRC from AA and CTRL. Predictive models based on random forest and the area under the curve (AUC) of the receiver operating characteristic curve (ROC) demonstrate that CEs, together with FIT measurement, improved the CRC and CTRL classification, but not AA. This study revealed that the AA group is a transitional stage with high heterogeneity. The increased tendency observed in CEs from CTRL to CRC might be related to the imbalance of cholesterol homeostasis due to cancer cells requiring a high cholesterol level for cell development and proliferation. The free cholesterol is probably obtained from CEs, as it is the most cost/effective way to obtain the needed cholesterol. Conclusions: The accumulation of CEs is produced by two possible approaches: (1) dysfunction of cholesterol absorption in the small intestine and/or (2) transported inside exosomes from cell to cell to promote proliferation.