Oral Cancer
Introduction and Prevalence
Oral cancer, which includes cancer of the lips, tongue and oral cavity, is a highly complex condition and can be life threatening if not diagnosed and treated at an early stage. It represents the eighth most commonly found form of cancer worldwide, but it has an uneven distribution where low-income countries bear the greatest burden [35, 36]. In these countries, oral cancer is twice as prevalent as it is in high-income countries. Head and neck cancer are also known to be more common among males compared to females, as well as being found more frequently in individuals of higher age. It was estimated that around 50,000 individuals would develop oral/oropharyngeal cancers in the USA in 2017 [37]. The oral cavity is made up of cells of different types and cancer can develop from each cell type, including the bone and salivary glands. The tumours can be (i) of benign or non-cancerous nature, (ii) pre-cancerous conditions or (iii) cancerous tumours, which may grow into the tissue and spread to other body parts. A total of >90% of oral cancers are oral squamous cell carcinoma with a higher incidence in Melanesian and South Asian countries [38].
Aetiology and Pathogenesis
Lifestyle plays a major role in oral cancer, and its incidence is particularly high in relation to risk factors such as tobacco smoking, excessive alcohol consumption, oral tobacco products, and frequent exposure to the sun [39–41]. Certain human papilloma viruses are also regarded as an aetiological risk factor [40]. The risk of oral cancer is 15 times higher among those who are both tobacco and alcohol users compared with those exposed to only one of these risk factors. Other potential risk factors include poor diet and nutrition, certain occupations, poorly fitting dentures, and poor oral hygiene.
Early diagnosis is important and may, just like other forms of cancer treatment, include surgery, radiation therapy or chemotherapy, often used in combination. The oral cavity is a sensitive area and the consequences of the disease itself, as well as the treatment, may affect quality of life. Conditions such as a reduced salivary secretion rate, facial disfigurement, speech impairment, and chewing/swallowing difficulties are commonly found. It is recommended that each individual should play an active role in detecting oral cancer at an early stage, conducting both a self-exam at home and undergoing examinations at a dental office on a regular basis. Smoking cessation should be encouraged and moderate alcohol consumption recommended.
Dry Mouth Conditions
Hyposalivation is a significant burden for many individuals and may affect various aspects related to the quality of life [42]. It plays a central role in taste, speech, cleaning, digestive function, protection of teeth, and control of oral microflora [43]. It is of particular protective importance in relation to dental caries. Saliva is produced by major and minor glands and is composed of >99% water and electrolytes. Salivary gland hypofunction can be seen as a consequence of several systemic conditions. This includes the medical area incorporating diseases such as Sjögren’s syndrome, eating disorders, and diabetes. A reduced salivary secretion rate may also be seen as a side-effect of radiation therapy in the head and neck area, as well as being due to a wide range of medications. Severe general malnutrition and particular nutrients may also affect salivary gland production. For those suffering from xerostomia and those with a suspected low secretion rate which may influence disease pattern, it is important to assess the salivary secretion level.
Acknowledgements
Figure 1c courtesy of Dr. B. Hasséus, Department of Oral Medicine and Pathology, Institute of Odontology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
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