Salivary cysteine levels as a potential biochemical indicator of oral cancer risk in tobacco consumers

<b>Aim:</b> Oral cancer is the leading cause of mortality, with a survival rate of less than 5 years, and is predominantly influenced by tobacco mutagens. Invasive diagnostic methods hinder early detection of oral cancer biomarkers. The present study performed salivary biochemical analysis for early oral cancer screening in tobacco consumers.<b>Materials & methods:</b> Three study groups included healthy controls (n = 25), tobacco users (n = 25) and oral cancer patients (n = 25). Salivary total protein, amylase, TNF-α and amino acid levels were evaluated using enzymatic tests, Enzyme linked Immunosorbent Assay (ELISA) and High-Performance Liquid Chromatography (HPLC).<b>Results:</b> Compared with healthy controls, salivary total protein and TNF-α levels were significantly (<i>p</i> = 0.04) higher in oral cancer patients. Salivary amylase levels were significantly lower in tobacco smokers (<i>p</i> = 0.02) and higher in oral cancer patients (<i>p</i> = 0.01). Interestingly, the amino acid cysteine concentration was significantly higher (<i>p</i> = 0.02) in tobacco consumers (62.5 ± 10) than in healthy controls (116.1 ± 28).<b>Conclusion:</b> In high-risk populations, such as tobacco users, salivary biochemical analysis can serve as a promising noninvasive diagnostic method for early oral cancer screening. As a salivary biomarker, the amino acid cysteine exhibits potential as a means of detecting the progression of oral cancer in individuals who consume tobacco.