Clinical contributions of exhaled volatile organic compounds in the diagnosis of lung cancer.

BACKGROUND: Exhaled volatile organic compounds (VOC) are being considered as biomarkers for various lungs diseases, including cancer. However, the accurate measurement of extremely low concentrations of VOC in expired air is technically challenging. We evaluated the clinical contribution of exhaled VOC measured with a new, double cold-trap method in the diagnosis of lung cancer. METHODS: Breath samples were collected from 116 patients with histologically confirmed lung cancer and 37 healthy volunteers (controls) after inspiration of purified air, synthesized through a cold-trap system. The exhaled VOC, trapped in the same system, were heat extracted. We analyzed 14 VOC with gas chromatography. RESULTS: The concentrations of exhaled cyclohexane and xylene were significantly higher in patients with lung cancer than in controls (p = 0.002 and 0.0001, respectively), increased significantly with the progression of the clinical stage of cancer (both p < 0.001), and decreased significantly after successful treatment of 6 patients with small cell lung cancer (p = 0.06 and 0.03, respectively). CONCLUSION: Measurements of exhaled VOCs by a double cold-trap method may help diagnose lung cancer and monitor its progression and regression.

Editor's Highlight: Prospective Analyses of Volatile Organic Compounds in Obstructive Sleep Apnea Patients.

Various volatile organic compounds (VOCs) are known to be toxic. Although exhaled VOC patterns change in obstructive sleep apnea (OSA) patients, individual VOC profiles are not fully determined. The primary outcome was VOC characterizations; secondary outcomes included their relationships with sleep and clinical parameters in OSA patients. We prospectively examined 32 OSA patients with an apnea-hypopnea index (AHI) ≥ 15 by full polysomnography, and 33 age- and sex-matched controls without obvious OSA symptoms. Nine severe OSA patients were examined before and after continuous positive airway pressure (CPAP) treatment. By applying a method which eliminates environmental VOC influences, exhaled VOCs were identified by gas chromatography (GC)-mass spectrometry, and their concentrations were determined by GC. Exhaled aromatic hydrocarbon concentrations (toluene, ethylbenzene, p-xylene, and phenylacetic acid) in the severe OSA groups (AHI ≥ 30) and exhaled saturated hydrocarbon concentrations (hexane, heptane, octane, nonane, and decane) in the most severe OSA group (AHI ≥ 60) were higher than those in the control group. Exhaled isoprene concentrations were increased in all OSA groups (AHI ≥ 15); acetone concentration was increased in the most severe OSA group. Ethylbenzene, p-xylene, phenylacetic acid, and nonane concentrations were increased according to OSA severity, and correlated with AHI, arousal index, and duration of percutaneous oxygen saturation (SpO2) ≤ 90%. Multiple regression analyses revealed these 4 VOC levels were associated with the duration of SpO2 ≤ 90%. Isoprene and acetone decreased after CPAP treatment. OSA increased some toxic VOCs, and some correlated with OSA severity. CPAP treatment possibly ameliorates these productions.