Exhaled volatile organic compounds identify patients with colorectal cancer

Abstract

Background: An effective screening tool for colorectal cancer is still lacking. Analysis of the volatile organic compounds (VOCs) linked to cancer is a new frontier in cancer screening, as tumour growth involves several metabolic changes leading to the production of specific compounds that can be detected in exhaled breath. This study investigated whether patients with colorectal cancer have a specific VOC pattern compared with the healthy population.Methods: Exhaled breath was collected in an inert bag (Tedlar  ) from patients with colorectal cancer and healthy controls (negative at colonoscopy), and processed offline by thermal-desorber gas chromatography-mass spectrometry to evaluate the VOC profile. During the trial phase VOCs of interest were identified and selected, and VOC patterns able to discriminate patients from controls were set up; in the validation phase their discriminant performance was tested on blinded samples. A probabilistic neural network (PNN) validated by the leave-one-out method was used to identify the pattern of VOCs that better discriminated between the two groups.

Blood volatile compounds as biomarkers for colorectal cancer

“…20 In recent years, many investigations have focused on analyzing CRC by determining the urinary metabolic profiles, blood levels of water-soluble metabolites, and exhaled VOCs of CRC patients. 8,15,21 To the best of our knowledge, no study has investigated the specific volatile metabolic biomarkers that exist in the blood of CRC. Chen performed a metabolomics analysis of the effects of CRC on urine and determined that relative to the urine of a control group of healthy individuals, the urine of CRC patients exhibited significantly higher levels of lactic acid but lower levels of histidine and methionine.…”

“…28 Altomare et al also identified various CRC-specific VOCs, including 2-methylbutane, cyclohexane, decanal, 4-methyl-2-pentanone, 1,2-pentadiene, 2-methylpentane, 4-methyloctane, methylcyclopentane, 3-methylpentane, methylcyclohexane, 1,3-dimethylbenzene, 1,4-dimethylbenzene, and nonanal. 15 These volatile biomarkers are mostly alkanes, ketones, aldehydes, and substituted benzene compounds. The mechanisms through which these metabolites are generated remains under investigation, although the majority of the extant studies support the hypothesis that these metabolites are produced in response to oxidative stress.…”

“…The mechanisms through which these metabolites are generated remains under investigation, although the majority of the extant studies support the hypothesis that these metabolites are produced in response to oxidative stress. 15,29 Tumor tissue demonstrates vigorous growth and consequently exhibits high energy demands. The malignant growth of cancer cells can lead to genetic mutations and the abnormal expression of proteins, causing the excessive oxidation of polyunsaturated fatty acids in cell membranes and/or the production of excessive reactive oxygen species (ROS).…”

“…13,14 In 2013, Altomare et al compared the composition of the exhaled VOCs of a CRC group with the exhaled VOCs of a normal control group and identified CRC-specific VOCs in exhaled breath. 15 However, the composition of exhaled breath is affected by many factors, such as lung disease, smoking, and diet. 16 VOCs are released into the bloodstream before they are exhaled; therefore, the analysis of VOCs in blood will provide more accurate results than the analysis of VOCs in exhaled breath.…”

Breath test: a new diagnostic tool for colorectal cancer?

“…A study recently published in the British Journal of Surgery provides new hope in this direction claiming that a breath analysis could earn a spot in the range of different screening tests for early detection of CRC [14]. The breath samples collected from 37 patients with histologically proven colorectal cancer, in addition to 41 healthy volunteers, were analyzed to assess how they differ in VOC composition.…”