Saliva as a first-line diagnostic tool: A spectral challenge for identification of cancer biomarkers

Abstract The paper concentrates on the role of saliva in the early diagnosis of salivary gland tumor. Due to the still not fully understood etiology of head and neck cancer, the fundamental objective of this study is to find tumor markers of salivary gland tumor progression. This work demonstrates the feasibility of Attenuated Total Reflection Fourier Transform Infrared spectroscopy (ATR-FTIR) to track spectral variations between saliva samples derived from healthy volunteers and from salivary gland tumor (tumor mixus, TM) patients. Furthermore, a Real-Time Polymerase Chain Reaction (RT-PCR) has been used to detect a selected genes expression associated with neoplasm changes. The obtained results imply that spectral signals attributed to the amide I/II (secondary structure of protein), carbohydrates and inorganic phosphates oscillations are the most sensitive to alterations associated with the salivary gland cancer progression. Several spectroscopic biomarkers have been indicated as potential predictors of salivary gland tumor development. Additionally, the RT-PCR results reveal the increased level of Bcl-2 factor in salivary gland tumor patients' samples which may be related to inhibition of apoptosis process and increasing uncontrolled cell proliferation. Such combination of physico-chemical methods is a unique approach towards better understanding the tumor's etiology and early diagnosis problem. Based on the promising findings presented in this article, it could be concluded that saliva fluid has a great potential to be used as a first-line diagnostic tool in patients with suspicion of salivary gland tumor.