Breath analysis can be used to diagnose diseases non-invasively. Accurate measurement of volatolomics is critical for breath analysis to be a gold standard. Tedlar bags (TB) are often used to collect breath samples, but they emit contaminants that affect accuracy. This issue was overlooked in previous studies. We found contamination issues with TB (e.g., siloxanes and aromatic impurities) that affect the identification of volatile organic compounds (VOCs) due to impurities. Then, home-designed equipment (HD) made with poly-tetrafluoride (PTFE) and quartz glass for breath collection was developed and employed in clinical trials. 15 healthy individuals and 32 non-small cell lung cancer (NSCLC) patients at IA stage participated in this study. 610 VOCs can be collected through TB, which is less than HD (1109 VOCs), demonstrating that the inner wall of the TB easily adsorbs VOCs, leading to decreased detection concentrations. Otherwise, utilizing orthogonal partial least squares discriminant analysis (OPLS-DA), we identified chemical markers with significant discriminatory power (VIP > 1.5, P < 0.05). The HD method identified 12 target VOCs, surpassing the 3 target VOCs discerned by the TB method. A model combined with a machine learning algorithm for distinguishing early-stage lung cancer patients was established based on biomarkers, which were selected based on OPLS-DA. The results showed strong predictive capabilities for the HD-based model. It indicated that 12 biomarkers derived from the HD model were more effective in distinguishing NSCLC patients, with an AUC value of 0.92, compared to the AUC value of 0.5 from 3 markers obtained from the TB model. The sensitivity and specificity in the confusion matrix reached 100% and 80% for the HD test, but TB test reached only 40% and 60%. This work demonstrated that optimizing and standardizing VOCs collection methodology from breath of lung cancer patients is essential to identify actual volatiles, which could promote disease volatolomics worldwide.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |