Oral / Mouth Cancer
Oral cancer includes all cases of cancerous tissue growth located in the mouth. Oral cancer is a form of cancer with one of the highest death rates of all cancers. The survival rate 5 years after diagnosis is only 50 percent, mainly due to late diagnosis.
Even when not fatal, oral cancer can result in chronic pain, loss of function, facial and oral disfigurement. Mouth cancer is the sixth most common type of cancer, more common than either skin or cervical cancer.
Early detection is critical. If oral cancer is diagnosed and treated in early stages, the recovery rate can be up to 80-90%. Oral or mouth cancer can be located anywhere in the oral cavity (lips, tongue, cheeks, floor of the mouth, gums, salivary glands, soft palate) with lips and tongue to be the most common. The majority of oral cancer patients are over 40 years old (50% are 68+), with men facing twice the risk than women.
Types of Mouth Cancer
There are two types of oral cancer based on the location of the cancer, oral cavity cancer and oropharyngeal cancer:
The oral cavity cancer is the type of mouth cancer located in:
- the lips, teeth, and gums
- the lining inside the lips and cheeks (buccal mucosa)
- the floor of the mouth (under the tongue)
- the top of the mouth (hard palate)
- the front part of the tongue
The oropharyngeal cancer is the type of mouth cancer located in:
- the back one-third of the tongue
- the soft palate
- the tonsils
- the back of the throat
Cancer of the mouth can be also categorized based on the type of cells where it is first developed:
- Almost 90 percent of the cases of oral cancer is squamous cell carcinoma. Squamous cells are the flat, skin like cells that cover the inside of the mouth, nose, larynx and throat. Squamous cell cancer begins with cancerous cells located on the surface of the lining of the mouth, later invading deeper in the mouth tissues and possibly spreading to the lymph nodes and other parts of the body.
- Salivary gland cancers
- Lymphomas, which are cancers that develop from cells in the lymph nodes.
- Melanomas, which develop from the cells that give the skin its colour. Melanomas of the head and neck can occur anywhere on the skin or inside the nose or mouth (oral cavity).
Other less common types of mouth cancer are:
What causes Oral Cancer
As all the other cancers, oral cancer results from the mutation of genes which control cell behavior. Cells that are unable to repair the DNA damage may become cancerous cells. Cells with mutated genes may start growing and multiplying at an uncontrolled rate. The uncontrolled growth causes the formation of a tumor.
Risk Factors for Cancer of the Mouth
Research has identified a number of risk factors that may contribute to damages of DNA and the development of oral cancer :
- Smoking or chewing tobacco. Tobacco is a chronic irritant that can cause damage to the cells of the mucosa of the oral cavity and upper throat. Cigarette, cigar, or pipe smokers are six times more likely to develop oral cancers than non smokers. Smokeless tobacco users are at even higher risk of cancers of the cheek and inner surface of the lips. Up to 75% of those diagnosed with oral cancer are tobacco users. Smoking is the main mouth cancer cause.
- Excessive alcohol consumption. Alcohol can also damage cells inside the mouth and upper throat. Oral cancers are about six times more common in drinkers than in non drinkers. The combination of alcohol and tobacco use increases significantly the risk of developing cancer of the mouth. Smokers who are also heavy alcohol users have a 15 times greater risk than others.
- Aging is frequently mentioned among the causes of mouth cancer, based in demographic data of oral cancer patients. Although aging cells may be more susceptible to DNA damages and malignant transformation, it is likely that the accumulated damage from other factors, such as tobacco use and alcohol consumption, are the real causes of mouth cancer.
- Human papilloma virus (HPV). HPV is a group of sexually transmitted viruses linked with more than 90% of cervical cancers. More recently, the human papilloma virus, particularly HPV16 and 18, has been implicated as a causative factor for some types of mouth cancers; and especially in the cases of younger non-smoking oral cancer patients.
- Excessive exposure to sun light. Prolonged exposure to sun or other source of ultraviolet radiation can cause cancers of the lips, as well as other skin cancers.
- Leukoplakia. A small percentage of leukoplakia patches may show early signs of cancer, and many mouth cancers occur in areas adjacent to leukoplakia patches.
- Erythroplakia. The majority of erythroplakia cases are eventually diagnosed as cancer. It is not clear if erythroplakia or leukoplakia are causes of oral cancer or just an early symptom of it.
It is important to note that over 25% of all oral cancers occur in people who have not been exposed to any of the above risk factors. Causes of mouth cancer in these cases remains unknown.
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