Breath Test Could Diagnose Colorectal Cancer

Analysis of the volatile organic compounds (VOCs), which can be detected in the breath of cancer patients, is a new frontier in cancer screening as malignant tissues have different metabolism compared to normal healthy cells.

A team of scientist at the University Aldo Moro (Bari, Italy) collected exhaled breath from 37 patients with colorectal cancer and 41 healthy controls, which was processed offline to evaluate the VOC profile. The VOCs of interest had been identified and selected, and VOC patterns were able to discriminate patients from controls.

Exhaled breath was collected in a Tedlar, inert bag (Sigma-Aldrich, St Gallen, Switzerland) from patients with colorectal cancer and healthy controls who were negative at colonoscopy, and processed by thermal‐desorber gas chromatography–mass spectrometry to evaluate the VOC profile. 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.

Some 37 patients and 41 controls were included in the trial phase. Application of a PNN to a pattern of 15 compounds showed a discriminant performance with a sensitivity of 86%, a specificity of 83%, and an accuracy of 85% calculated as the area under the receiver operating characteristic (ROC) curve .The accuracy of PNN analysis was confirmed in the validation phase on a further 25 subjects and the model correctly assigned 19 patients, giving an overall accuracy of 76%.

Levels of some specific VOCs such as 1,3-dimethylbenzene, 1,2-pentadiene, cyclohexane, methylcyclohexane and 4-methyloctane were higher in patients with colorectal cancer than in controls. The authors concluded that the pattern of VOCs in patients with colorectal cancer was different from that in healthy controls. The PNN in this study was able to discriminate patients with colorectal cancer with an accuracy of over 75 %. Exhaled breath VOC analysis appears to have potential clinical application in colorectal cancer screening, although further studies are required to confirm its reliability in heterogeneous clinical settings.

Donato F. Altomare, MD, the senior author said, “The technique of breath sampling is very easy and noninvasive, although the method is still in the early phase of development. Our study's findings provide further support for the value of breath testing as a screening tool." The study was published on December 5, 2012, in the journal British Journal of Surgery (BJS).

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