Oral cancer typically begins as a small, unexplained growth or sore in various parts of the mouth, such as the lips, cheeks, tongue, sinuses, hard and soft palate, the floor of the mouth, and extending to the oropharynx. Globally, it is the sixth most common type of cancer. India accounts for the highest number of oral cancer cases, contributing to one-third of the global burden. Compared to Western countries, the burden of oral cancer in India is considerably higher, with approximately 70% of cases being diagnosed at advanced stages (Stage III-IV, according to the American Joint Committee on Cancer). Due to this late-stage detection, the likelihood of successful treatment is significantly reduced, resulting in a five-year survival rate of only around 20%. Oral squamous cell carcinoma (OSCC) accounts for a significant proportion of oral cancer cases, contributing approximately 84.97%. OSCC often arises from either normal epithelial linings or potentially malignant lesions. Potentially malignant disorders (PMDs), including inflammatory oral submucosal fibrosis, erythroplakia, leukoplakia, candidal leukoplakia, dyskeratosis congenita, and lichen planus, serve as key indicators of the preclinical stage of oral cancer. Several risk factors are associated with the development of oral cancer, including the use of tobacco products—particularly smokeless tobacco (SLT), betel-quid chewing, excessive alcohol intake, poor oral hygiene, nutrient-deficient diets, and persistent viral infections such as human papillomavirus (HPV). Additionally, limited awareness, exposure to harsh environmental conditions, and various behavioral risk factors contribute to the wide global variation in oral cancer incidence. Periodontal diseases also represent a significant risk factor for oral malignancies. In the Indian context, the high prevalence of oral cancer is largely attributed to the widespread practice of chewing paan. Oral squamous cell carcinoma (OSCC) most frequently affects the middle-aged population; however, its incidence among younger individuals is also on the rise. The tongue is the most commonly affected site, followed by the floor of the mouth. Less frequently involved areas include the gingiva, buccal mucosa, labial mucosa, and hard palate. The survival rate for OSCC is significantly higher—around 80%—when detected at an early stage (Stage I), compared to only 20–30% for those diagnosed at advanced stages (Stages III–IV). This highlights the critical importance of early detection. Despite this,

approximately 50% of OSCC cases are still diagnosed at advanced stages, which contributes to poorer prognoses, increased treatment costs, and higher mortality rates.

Conventional biopsy remains the gold standard for diagnosing oral squamous cell carcinoma (OSCC). However, its application in large-scale population screening and ongoing patient monitoring is limited due to its invasive nature, high cost, and the requirement for specialized personnel and equipment. In contrast, metabolomics utilizes advanced analytical technologies to detect and analyze metabolic changes in individuals experiencing pathological conditions, pharmacological treatments, or genetic alterations, offering a less invasive and potentially more scalable alternative for early detection and monitoring. Biofluids such as urine, blood, and saliva are commonly utilized as clinical samples in metabolomic analyses. Among these, saliva is particularly valuable as it reflects both oral and systemic health conditions. Saliva is a complex biological fluid composed of a wide range of constituents, including proteins, peptides, nucleic acids, enzymes, hormones, antibodies, electrolytes, antimicrobial agents, growth factors, and various other molecules. These components provide insights into an individual’s physiological state and are often linked to specific phenotypes and disease conditions.

Previous research has identified several metabolomic biomarkers associated with oral squamous cell carcinoma (OSCC). Investigating the salivary metabolome in OSCC focuses on detecting significantly altered metabolic pathways, which may lead to the identification of potential diagnostic biomarkers. Such advancements could enhance early detection capabilities and, in turn, improve patient outcomes and quality of life. Among the various analytical techniques used in metabolomics, gas chromatography–mass spectrometry (GC-MS) is one of the most widely employed. Gas chromatography separates compounds based on differences in boiling points, polarity, and their adsorption rate on the column surface. Mass spectrometry then analyses these compounds by measuring their mass-to-charge ratio, making GC-MS a powerful tool for both qualitative and quantitative analysis of complex biological samples