Volatile organic compounds as new biomarkers for colorectal cancer: a review

Abstract

Analysis of the volatile part of the metabolome (volatile organic compounds, VOC) present in the gas phase of excreted materials is a promising new screening tool for several cancers, including colorectal cancer (CRC). The VOC signature can reflect health status, like a 'fingerprint', and can be modified in several diseases. Technical difficulties still limit the widespread use of VOC analysis in the clinical setting, but this approach has already been applied successfully in the diagnosis of CRC. The present study reviews the available data on VOC present in the headspace (the gaseous constituents of a closed space above a liquid or solid) of blood, urine, faeces and breath as a potential screening tool for CRC. A systematic electronic literature search was conducted in PubMed, Scirus and Google using the following keywords: Metabolomic, Volatile Organic Compounds (VOC), Electronic-nose and Colorectal Cancer. Only articles published in English between 2000 and 2015 were selected and these were independently checked by two of the authors. Ten papers describing the reliability of VOC analysis in breath and faeces, blood and urine were selected; all indicated good reliability in detecting CRC. The use of different substrates and different analytical platforms has led to the identification of different patterns of VOC. The reliability of a metabolomic approach as a noninvasive biomarker for use in CRC screening is supported by this review despite several limitations due to the number of patients included in each study, the different analytical platforms and biological materials used and different VOC identified.

GC‐MS metabolomics‐based approach for the identification of a potential VOC‐biomarker panel in the urine of renal cell carcinoma patients

“…In the present study, the volatile profile of human urine was studied, in an attempt to reveal a VOC‐biomarker panel for non‐invasive detection of this cancer. Despite the potential of VOCs for the discrimination between cancer and control samples being currently acknowledged , concerning RCC, the potentialities of human urine volatilome for that purpose are scarcely exploited .…”

Detection of halitosis in breath: Between the past, present, and future

“…Gastrointestinal (GIT) diseases could induce exhaled volatolome alterations via two main pathways: (i) esophageal release of VOCs through the upper gastric sphincter to the oral cavity, and/or (ii) adsorption of VOCs from the GIT tract into the blood stream and subsequent diffusion via the lungs into the exhaled breath (Carlini & Ligabue‐Braun, ; Di Lena, Porcelli, & Altomare, ). Searches for non‐invasive biomarkers in GIT diseases have repeatedly identified distinctive volatolomic profiles in exhaled breath.…”

Volatile organic compounds in bile can distinguish pancreatic cancer from chronic pancreatitis: a prospective observational study

“…Volatile organic compounds (VOCs) are chemicals with high vapor pressures, which allow them to easily diffuse out of the solids and liquids in which they are contained and enter their gaseous forms [3]. In the past decade, VOCs in the breath, blood, urine, and feces have been increasingly investigated as potential noninvasive diagnostic biomarkers for a myriad of diseases [4,5]. Concentrations of VOCs can be determined by analyzing the gaseous headspace over liquid samples, and thus VOCs in the biliary headspace may offer early evidence of the presence of pancreatic cancer given the intimate association between the biliary tree and pancreatic parenchyma [6,7].…”