Volatile Organic Compounds From Healthy and Oral Cancer Saliva Samples

Objectives: Cancer is the most common cause of death in Japan and its early detection becomes a key factor for effective treatment. Diagnosis is often based on serum and/or tissue levels of specific DNA and proteins. Recently, odorous molecules excreted from the body have attracted interest, as some related molecules, known as low-molecular-weight volatile organic compounds (VOCs), have shown a strong correlation with the pathology of certain conditions. Human saliva contains peptides and proteins, as well as numerous VOCs, thus in addition to a role in oral health, saliva may also hold keys to chemical communication. In this study, we used thin-film microextraction (TFME) and gas chromatography–mass spectrometry (GC–MS) techniques to examine saliva samples for possible use in cancer diagnosis.
Methods: Saliva samples from 8 healthy volunteers and 11 patients with tongue cancer were collected, with all oral intake, tooth brushing, and smoking prohibited for at least 30 minutes prior to sampling. From each, 2 ml of saliva was diluted with 3 ml of deionized water, then the aqueous solution samples were placed in polydimethylsiloxane (PDMS)-based ZSM-5 (aluminosilicate zeolite) hybrid film-coated sample bottles for 3 hours at 30°C. Next, methanol (100 μL) was used to release VOCs from the thin film for 30 minutes at 30°C. Finally, each methanol sample (1.0 μL) was injected into the GC port for analysis.
Results: Approximately 50-100 different VOCs were identified in each saliva sample by GC-MS analysis, with additional detailed information regarding oral VOCs obtained from principal component analysis (PCA)-based statistical findings. Our results showed that VOCs are able to distinguish between healthy subjects and cancer patients.
Conclusions: Our findings suggest the possibility of new biomarkers useful for reflecting oral cancer progression.