| Oral cancer is reported as the sixth most frequently occurring malignancy all over the world. The burden of oral cancer is much higher in developing countries compared to Western countries. This accounts for almost 40% of all cancers in the Indian subcontinent and contributed one-third of the world burden of oral cancer. The common potentially malignant oral disorders (PMODs) seen in India such as leukoplakia, erosive lichen planus, oral submucous fibrosis are more likely to transform into malignancy than the general population, and PMODs are thus considered to be a warning sign for the development of OSCC. Despite of recent therapeutic advances, oral cancer has one of the lowest survival rates. For oral squamous cell carcinoma (OSCC), the overall 5-year survival rate is approximately 50%, and unchanged over the last 30 years mainly due to delayed diagnosis, underdiagnosis or misdiagnosis. But if the disease can be detected early, treatment can be given more effectively, and consequently the survival rate can also be increased. For OSCCs which were detected early i.e soon after the transition from premalignancy, the survival rate after giving effective treatment has increased to about 80%. Thus, early diagnosis and appropriate treatment at the right time is highly essential. This shows the importance of potentially malignant disorders which if diagnosed and treated early can reduce the incidence of oral carcinoma to a great extent. At present, biopsy for histopathologic examination is used for the definite diagnosis of OSCC and PMODs.
But its disadvantages, includes that it is time-consuming, has a high cost, and isinvasive causing destruction to human tissues. Furthermore, some clinical auxiliary examinations for PMODs, such as autofluorescence imaging, aceto-whitening and toluidine blue in vivo staining, have poor diagnostic accuracy and give high false-positive results. Therefore, finding a conventional diagnostic method with high sensitivity and specificity is extremely important for the diagnosis of OSCC and PMODs. Considering the facts such as delayed detection likely to be a primary reason for the high morbidity and mortality rates of oral cancer patients and the disadvantages of the current diagnostic methods, there is a need for finding a new method to perk up early detection of oral cancers. Biomarkers are measurable nano-protein which is used to predict a biological state. These can be detected in serum, saliva, and tissue using convenient and rapid methods. There is a constant search for biomarkers in saliva, a body fluid that can be easily collected, for noninvasive detection of oral cancer and precancer. Levels of over 100 salivary biomarkers for oral malignancies have been identified as changing significantly in OSCC patients, but these markers exhibited a low value to detect OSCC. Therefore, it is needed to explore a more ideal marker for OSCC and PMODs. The diagnosis and prognosis prediction of oral cancer can be made simple by using saliva as a tool with the help of an ideal salivary biomarker. It should be a cost-effective method which could easily be employed to screen large populations. The synuclein protein family is a small, soluble proteome composed of synuclein-α, synuclein-β and synuclein-γ (SNCG), originally found in brain tissue, peripheral nerve tissue, and retina, which is involved in neurodegenerative diseases and cancers. SNCG expression is an early step in the malignant transformation of oral epithelium. Interleukin-6 (IL-6) and interleukin-8 (IL-8) are multifunctional cytokines that is associated with cancer in various ways. Recently, they are also found to be increased in the saliva of oral precancer and cancer patients, which could serve as a biomarker.The excessive production of IL-6 and IL-8 plays a role in cancer progression and establishment of angiogenesis. IL-8 levels are found to be same in serum and saliva and is elevated in PMODs making it as a valuable biomarker. A study on evaluation of SNCG levels in saliva and cancer tissues from oral squamous cell carcinoma patients and another study on assessment of serum SNCG and squamous cell carcinoma antigen as diagnostic biomarkers in patients with PMODs and OSCC were conducted earlier, but no studies have been conducted to assess the level of salivary SNCG in patients with OSCC and PMODs and correlated the findings with levels of salivary IL-6 and IL-8 for identifying the diagnostic value of SNCG as a biomarker as well as using the combination of salivary SNCG, IL-6 and IL-8 for diagnosis and prognosis of OSCCs and PMODs.
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