Oral Cavity and Major and Minor Salivary Glands

Abstract

Cancer of the oral cavity is almost synonymous with squamous cell carcinoma as 90% of cancers in the oral mucosa appear to be of this type. The sixth most common oral malignancy is the different types of adenocarcinoma arising from salivary glands. A small proportion of cancers in the oral cavity are composed of melanoma, lymphoma, and various types of sarcomas. Oral squamous cell carcinoma is the sixth common malignancy and is a major cause of cancer morbidity and mortality worldwide. Although the aetiology is thought to be multifactorial, tobacco use in many different forms appears to play a major role. It is clear that various other factors such as genetic susceptibility, alcohol, nutritional deficiencies, viruses, fungi, and ultraviolet light have either a synergistic role or direct effect on oral carcinogenesis. A significant number of cases occur in a background of either a precancerous lesion or a precancerous condition. Molecular markers which have been investigated for determining different aspects of oral cancer can be classified into DNA content (ploidy), loss of heterozygosity, expression of oncogenes and onco‐suppressor genes, proliferation markers, and differentiation markers. However, prediction of malignant transformation of precancers and prognosis of oral cancers with the help of molecular markers need further research. Despite the advancement in treatment involving surgery, chemotherapy, and radiotherapy, the long‐term survival has been less than 50% with no significant improvement in prognosis over the last four decades. Salivary neoplasms account for up to 2% of all neoplasms in the head and neck. Although the exact aetiology of salivary gland tumours is far from clear, various aetiological factors such as radiation, viruses, occupational, hormonal, nutritional, and smoking have been suggested. Unlike most cancers, salivary tumours do not show any evidence of familial predisposition. Surprisingly, only a few studies have been carried out on salivary tumours in order to investigate molecular aspects. Prognosis of salivary tumours mostly depends on microscopical grade and tumour type. Surgery is the treatment of choice for a large majority of both benign and malignant salivary tumours. Chemotherapy and radiotherapy are used mostly as palliative measures.

Current concepts and future of noninvasive procedures for diagnosing oral squamous cell carcinoma - a systematic review

“…Such mutations have been identified in 46% of patients with head and neck cancer [ 45 ], and have been identified by direct sequencing in 67% of saliva samples from OSCC patients [ 45 , 46 ]. The p53 gene, which is located on chromosome 17p13.1, exhibits mutation in 50–70% of epithelial tumours [ 47 , 48 ]. Loss of heterozygosity of the p53 allele has been reported in 22% of cases of pre-cancer and 20% of oral cancer.…”

“…Loss of heterozygosity of the p53 allele has been reported in 22% of cases of pre-cancer and 20% of oral cancer. Other genes related to p53 and the cell cycle, such as p16, p27, p63, and p73 have been found to be altered to varying degrees in oral cancer [ 47 , 48 ]. Using plaque hybridisation, Boyle et al [ 48 ] identified tumour-specific p53 mutations in 71% of saliva samples from patients with head and neck cancer.…”

Role of Salivary Biomarkers in Oral Cancer Detection- A Systematic Review

“…9 Other genes such as p16, p27, p63, p73 related to p53, and cell cycle are altered in varying degrees in oral cancer. 10 Main functional activity of p53 is cell cycle arrest and initiation of apoptosis in response to the DNA damage.…”

A Review of Salivary Biomarker: A Tool for Early Oral Cancer Diagnosis

“…[ 32 ] Other genes such as p16, p27, p63, p73 related to p53, and cell cycle are altered in varying degrees in oral cancer. [ 33 ]…”