The Dual Role of Saliva in Oral Carcinogenesis

Abstract

Oral squamous cell carcinoma (OSCC), the most common head and neck malignancy, represents a serious public health problem. Exposure to cigarette smoke (CS)/tobacco is considered responsible for up to 90% of cases of this cancer worldwide. Free radicals, which often originate in CS and reactive nitrogen species, are frequently considered to be the reagents capable of triggering the process leading to malignant transformation. Initially dysplastic lesions of the mucosa are transformed into in situ carcinoma lesions, eventually resulting in a full-blown infiltrating and metastasizing OSCC. A synergistic, deleterious interaction between CS and saliva has been reported, which may result in the rapid destruction of biological macromolecules such as enzymes and proteins, giving it a possible pivotal role in the pathogenesis of OSCC. This lethal synergistic effect of CS and saliva is probably based on the reaction between redox-active metals in saliva and low reactive free radicals in CS. This is a novel concept recognizing that when exposed to CS, salivary behavior is reversed and saliva loses its antioxidant capacity, becoming a potent pro-oxidant milieu.

The Effect of Tobacco Smoking on Salivation

“…Recent research confirms that smoking negatively affects the quality of saliva. Substances from cigarette smoke destroy protective macromolecules of saliva, enzymes and proteins, and thus saliva loses its protective role and becomes an agent in carcinogenesis and development of oral and oropharyngeal cancer (10)(11)(12).…”

Tobacco Smoke–Induced Immunologic Changes May Contribute to Oral Carcinogenesis

“…More than sixty carcinogens are found in TS and smoking is a major risk factor for development of malignancies of the aerodigestive tract including the oral cavity [2,3]. Oral squamous cell carcinoma is the most common head and neck malignancy and the sixth most common cancer in the world [4]. Tobacco exposure is believed to be responsible for up to 90% of cases of oral squamous cell carcinoma [5,6].…”

“…2,3 Oral squamous cell carcinoma is the most common head and neck malignancy and the sixth most common cancer in the world. 4 Tobacco exposure is believed to be responsible for up to 90% of cases of oral squamous cell carcinoma. 5,6 Carcinogens in TS induce DNA mutations leading to oral squamous cell carcinoma.…”

Analysis of Salivary Antioxidant Levels in Different Clinical Staging and Histological Grading of Oral Squamous Cell Carcinoma: Noninvasive Technique in Dentistry

“…reactive oxygen species cause loss of salivary antioxidant capacity lead development of oral cancer in many tobacco chewers and smokers [4,5]. Antioxidants, on the other hand have a protective role by scavenging the free radicals [6].…”