Salivary Oxidative Stress Biomarkers in Oral Potentially Malignant Disorders and Squamous Cell Carcinoma

Abstract

Tumor biomarkers are endogenous or exogenous compounds that are produced either by the tumor cells themselves or by the normal cells in response to the presence of the tumor. These biomarkers are either found in the tumor tissue or in the various circulating body fluids like blood, saliva, urine, and cerebrospinal fluid. The identification of various tumor biomarkers is of considerable importance in early diagnosis, treatment, and improved prognosis of various human malignancies. The use of saliva as a diagnostic tool for identification of various tumor biomarkers has gained traction in the recent past owing to easy, noninvasive nature of saliva collection and the improved ability to identify numerous biomarkers even when present in minute quantities. Oral squamous cell carcinoma is an important epithelial malignancy of oral cavity with increased morbidity and mortality that may either occur de-novo or from precursor lesions which are collectively known as oral potentially malignant disorders. Oxidative stress occurs because of an imbalance between free radical generation and antioxidant defense system which is considered to play a potential role in oral carcinogenesis. The end products of oxidative stress-related processes are differentially regulated in oral cancer and are commonly found in the circulating fluids including saliva. With the technological advancements, improved sensitivity, and the close proximity of saliva to the oral lesions, the identification of these end products in oral cancer and their precursor lesions could be useful as potential biomarker for early detection, preventing the malignant transformation and improved prognosis.