Volatile Breath Compounds Associated with Laryngeal Carcinomas

Exhaled breath contains thousands of gaseous volatile organic compounds (VOCs) that may be used as noninvasive markers of head and neck epidermoid cancer.

The technique of solid phase microextraction (SPME) may be useful for the analysis of exhaled air and it is one of the methods used to concentrate volatile organic compounds emitted by different sources.

Scientists at the Rey Juan Carlos University (Madrid, Spain) and the Foundation Hospital (Alcorcón, Spain) compared the volatile substances exhaled by 11 people with cancer of larynx in various phases of the disease, with those of another 20 healthy people, half of whom were smokers. The participants exhaled breath into tedlar bags after fasting for at least eight hours so there was no leftover food or drink on their breath.

The samples were then analyzed with solid phase microextraction, gas chromatography and mass spectrometry equipment (Agilent [Varian inc.], Palo Alto, CA, USA) which enable very small amounts of a substance to be separated and identified. The concentrations are around or slightly above the equipment's detection limits, 40 ng/mL, which is equivalent to 40 ppb (parts per billion).

The investigators found that that the air exhaled by the more seriously ill patients, in a stage called T3, contains different concentrations of seven compounds compared with the levels of healthy people or even those with a less developed tumor (T1). Specifically, in the graphics of individuals with advanced cancer, the peaks that represent ethanol (C₂H₆O) and 2-butanone (C₄H₈O) are particularly significant. These two compounds therefore become potential markers of laryngeal carcinoma.

A total of 31 common VOCs in non-smokers have been determined, whereas smokers reach up to 45 VOCs, thus differentiating the two types of populations. The study also identified four markers in the exhaled breath that are typical of smokers, such as benzene and furfural. The four marker compounds that were found and related to cigarette smoking but absent in nonsmokers, and these were: cyclohexa-1,3,5-triene (benzene), fural-dehyde, 4-isobutyl-1-(1-hydroxyethyl)-benzene, and 2,3,5-trimethylhexane.

Rafael A.García, PhD, a professor of Chemical Engineering, and lead author of the study said, “At the moment it is still a preliminary study and a wider sample has to be obtained but it is a step in the right direction, an alternative with regard to identifying biomarkers, not only for this type of cancer but for other more prevalent and serious ones such as lung cancer, where early detection is key.” The study was published in the March 2014 issue of the journal Chromatographia.

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Rey Juan Carlos University
Foundation Hospital
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