**3. Biomarkers in oral squamous cell carcinoma (OSCC)**

Early detection of OSCC improves life quality while lowering the cost and side effects of medical treatments. Because OSCC has such a high recurrence

*Way to Cure Oral Squamous Cell Carcinoma with Theranostics and Nanoparticular Approaches DOI: http://dx.doi.org/10.5772/intechopen.100181*

rate, early detection is crucial in determining the disease's prognosis [15]. OSCC remains a significant challenge due to the disease's nature, despite recent advances in this area. As a result, as discussed in this book chapter, monitoring the level of biologic markers with high specificity and sensitivity is a promising diagnostic tool for both primary and recurrent oral cancer detections. According to the National Institutes of Health, biomarkers are indices of normal or pathological conditions that can be reliably and precisely measured [16]. Mutated DNA, mRNA, metabolomes, secreted proteins, and small molecules are examples of biomarkers [17, 18]. A cancer biomarker is a molecule that is secreted by a tumor or produced in response to the onset or progression of cancer. In addition, the ideal biomarker should be a noninvasive method with high-positive and high-negative predictive values that reflect the stage of cancer. As a result, the marker can be used to predict treatment efficacy, diagnosis, and prognosis in cancer patients.

#### **3.1 OSCC salivary biomarkers**

Saliva collection is easy and painless, making it a promising biomarker discovery tool. The changes in the saliva genome and protein profile after the onset of cancer or as the disease progresses in oral cancer have been studied in several studies [19, 20]. When collecting, processing, and storing saliva, however, some acquaintances should be considered. Cross-validation is required before extrapolating biomarkers into clinical applications. Different data collection, processing, and analysis techniques could explain the wide range of results seen in studies looking for salivary oral cancer biomarkers. As a result, more research is needed to standardize the aforementioned techniques as well as reference levels in order to obtain valid biomarkers.

#### **3.2 Salivary RNA-base biomarkers**

In the mouth, salivary RNAases were supposed to break down RNA. These alluring biomarkers, on the other hand, are obstinate, being carried in apoptotic bodies or actively liberated from cellular vesicles such as exosomes. Oral cancer patients have been found to have low levels of miRNA 200a and miRNA 125a, but significantly higher levels of miRNA 31. Upregulated miRNA 184 and downregulated miRNA 145 have also been linked to malignant oral cancer.

#### **3.3 Salivary protein-based biomarkers**

Cancer biomarkers could include oxidative stress markers. Carbonylation causes irreversible protein damage, which leads to cell toxicity. In OSCC patients, the infiltration of reactive radicals into the oral epithelial cells results in a significant increase in salivary carbonyls. Matrix metalloproteases (MMPs) are enzymes that degrade a wide range of proteins. During OSCC, which is highly invasive and metastatic, different types of MMPs have been shown to be significantly altered. MMP-2 and MMP-9 expression in oral cancer patients has been linked to a poor prognosis in the wild. The immune system produces proteins called interleukins (IL). In cellular signaling cascades, naturally occurring proteins play a variety of roles, some of which are critical in cancer. Interleukin-6 (IL-6) and interleukin-8 (IL-8) are two different types of interleukin-6. The prevalence of OSCC has been reported to be on the rise. The cytokeratin fragment 21–1 is a squamous tumor marker (Cyfra 21–1).
