Volatile organic compounds in breath as markers of lung cancer: a cross-sectional study

Background. Many volatile organic compounds (VOCs), principally alkanes and benzene derivatives, have been identified in breath from patients with lun g cancer. We investigated whether a combination of VOCs could identify such patients. Methods. We collected breath samples from 108 patients with an abnormal che st radiograph who were scheduled for bronchoscopy. The samples were collect ed with a portable apparatus, then essayed by gas chromatography and mass s pectroscopy. The alveolar gradient of each breath VOC, the difference betwe en the amount in breath and in air, was calculated. Forward stepwise discri minant analysis was used to identify VOCs that discriminated between patien ts with and without lung cancer. Findings. Lung cancer was confirmed histologically in 60 patients. A combin ation of 22 breath VOCs, predominantly alkanes, alkane derivatives, and ben zene derivatives, discriminated between patients with and without lung canc er, regardless of stage (all p < 0.0003). For stage 1 lung cancer, the 22 V OCs had 100% sensitivity and 81.3% specificity. Cross-validation of the com bination correctly predicted the diagnosis in 71.7% patients with lung canc er and 66.7% of those without lung cancer. Interpretation. In patients with an abnormal chest radiograph, a combinatio n of 22 VOCs in breath samples distinguished between patients with and with out lung cancer. Prospective studies are needed to confirm the usefulness o f breath VOCS for detecting lung cancer in the general population.