Carbonyl Compounds in Breath Could Help Diagnose Lung Cancer

Six carbonyl compounds in exhaled breath effectively discriminate between lung cancer patients and healthy controls as well as in those with benign pulmonary nodules, according to a new study. This could be used to easily detect the presence of malignancy.

“Growth of cancer cells in an unstable redox environment is thought to cause oxidative stress and the production of detectable [volatile organic compounds] in exhaled breath,” wrote study authors led by Mingxiao Li, of the University of Louisville in Kentucky.

Previous methods used to try and detect these compounds in breath have been limited in various ways; the new study focused on a novel method utilizing “quaternary aminooxy-coated silicon microreactors” to identify and quantify specific volatile compounds in exhaled breath. The method was tested in 85 patients with untreated lung cancer, 34 patients with benign pulmonary nodules, and 85 healthy controls divided by smoking status. Results were published online ahead of print in Lung Cancer.

They found that six specific carbonyl compounds had elevated concentrations in the breath of lung cancer patients compared to healthy controls. These included: 2-butanone; a mixture of 2-pentanone and pentanal; hydroxyacetaldehyde; 3-hydroxy-2-butanone; 4-hydroxy-2-hexenal; and 4-hydroxy-2-nonenal.

The researchers created model based on counting the number of elevated compounds out of these six. It had a classification accuracy for finding lung cancer patients vs non-smoker controls of 97%. The accuracy was 95% for lung cancer patients vs current smoker controls, and 89% for lung cancer patients vs patients with benign pulmonary nodules.

The sensitivity in each of these cases was 96% or above. The specificity ranged from 64% for patients with benign nodules, to 86% for healthy controls who smoked, to 100% for non-smoking healthy controls.

“This study demonstrates that the six markers in exhaled breath can be used for distinguishing patients with lung cancer from patients with benign pulmonary nodules and healthy subjects,” the authors concluded. “A study with a larger study population is required to verify the method.” This adds to a growing body of research on using breath to help diagnose lung cancer, including recent work on the use of a temperature cutoff to identify lung cancer patients.