Oral cancer: Squamous cell carcinoma of the floor of the mouth

• What is Oral Cancer (Squamous Cell Carcinoma of the Floor of the Mouth)
• Statistics on Oral Cancer (Squamous Cell Carcinoma of the Floor of the Mouth)
• Risk Factors for Oral Cancer (Squamous Cell Carcinoma of the Floor of the Mouth)
• Progression of Oral Cancer (Squamous Cell Carcinoma of the Floor of the Mouth)
• Symptoms of Oral Cancer (Squamous Cell Carcinoma of the Floor of the Mouth)
• Clinical Examination of Oral Cancer (Squamous Cell Carcinoma of the Floor of the Mouth)
• How is Oral Cancer (Squamous Cell Carcinoma of the Floor of the Mouth) Diagnosed?
• Prognosis of Oral Cancer (Squamous Cell Carcinoma of the Floor of the Mouth)
• How is Oral Cancer (Squamous Cell Carcinoma of the Floor of the Mouth) Treated?

What is Oral Cancer (Squamous Cell Carcinoma of the Floor of the Mouth)

Oral Cancer (Squamous Cell Carcinoma of the Floor of the Mouth) in oncology squamous cell cancers of the head and neck are often considered together because they share many similarities – in incidence, cancer type, predisposing factors, pathological features, treatment and prognosis. Up to 30% of patients with one primary head and neck tumour will have a second primary malignancy. The oral cavity or mouth consists of two parts: the vestibule, which is the space between the lips and cheeks and the teeth and gums; and the mouth proper which is internal to the teeth. The oral cavity refers to the entire contents of this area – including the cheeks, gums, teeth, tongue and palate. The functions of this region include ingestion, the first phases of digestion of food (mechanical destruction by the teeth through chewing), taste, respiration and the function of speech (with the movements of the oral cavity and its components shaping the sounds produced by the larynx into words). The floor of the mouth is the area between the mandible (jaw bone) and the attachment of the muscles of the tongue. It is lined by a thin mucous membrane and contains the sublingual salivary glands and the lingual frenulum (a loose attachment to the tongue).

Statistics on Oral Cancer (Squamous Cell Carcinoma of the Floor of the Mouth)

Oral cancer is relatively common, with 3% of all malignancies arising within the oral cavity, and it occurs with increasing age. It is uncommon before the age of 40, and the highest incidence of oral cancer is in the 6th and 7th decades with sex incidence being a 2:1 male predominance. Geographically, the oral cacner tumour is found worldwide, but there is significant variation in incidence. Oral cancer occurs with highest incidence in African and Asian countries.

Risk Factors for Oral Cancer (Squamous Cell Carcinoma of the Floor of the Mouth)

All oral cancers show a strong association with alcohol consumption and tobacco smoking, particularly of cigarettes – in fact, tobacco is thought to be implicated in well over 80% of cases of oral cancers. Chronic exposure of the epithelial surfaces of the head and neck to these irritants are thought to result in a “field cancerisation” sequence of hyperplasia, dysplasia and carcinoma. That is, the development of premalignant lesions that may then undergo malignant change to become an oral cancer. Smoking and alcohol act synergistically in the development of oral cancer – the risk when both of these factors is present is more than double the risk of exposure to one factor alone. There is a dose-response relationship between exposure to tobacco smoke and the development of oral cancer – the more you smoke the greater the risk of oral cancer. Smokers are up to 25 times more likely to develop head and neck cancer than their non-smoking counterparts. Passive smoking, tobacco chewing and cigar smoking are also risk factors for the development oral cancer. Up to the point of development of overt carcinoma, many of the changes associated with cigarette smoking will reverse if the patient quits smoking. Alcohol consumption as a risk factor for the development of oral cancer also shows a dose-response relationship – with heavy drinkers being at greater risk. In addition, drinkers of spirits may be at a greater risk than those who drink wine. Chronic viral infection is also associated with the development of oral cancer. Epstein-Barr Virus is strongly associated with the development of nasopharyngeal cancer, whilst Herpes Simplex Virus and Human Immunodeficieny Virus have been associated with the development of a number of different oral cancers. This is thought to be due to their interference with the function of tumour suppressor genes and oncogenes. HPV 16 and 18 are particularly associated with cancers of the oral cavity. Other risk factors or oral cancer include immune deficient states (such as post solid-organ transplant); occupational exposures to agents such as asbestos and perchloroethylene; radiation; dietary factors; a genetic predisposition to the development of oral cancer; and poor oral hygiene. Cancers of the oral cavity occur with highest incidence in countries where the betel nut is chewed. With cancers of the lips, sun exposure is an additional risk factor in development.

Progression of Oral Cancer (Squamous Cell Carcinoma of the Floor of the Mouth)

This type of tumour spreads by local extension and the destruction of adjacent tissue, with invasion of the tongue and mandible common. Lymphatic invasion with spread to the cervical lymph nodes is common at diagnosis. Haematogenous spread to distant sites such as the liver, bones and lungs may also have occurred at the time of diagnosis.

How is Oral Cancer (Squamous Cell Carcinoma of the Floor of the Mouth) Diagnosed?

Oral cacner general investigations may show anaemia or abnormal liver function tests if the disease is very advanced, or due to the aetiology of the oral cacner. General investigations in the early stage of cancer ot the oral cavity tend to be normal.

Prognosis of Oral Cancer (Squamous Cell Carcinoma of the Floor of the Mouth)

Early oral cancer diagnosis is the key prognostic factor in cancer – of the floor of the mouth – influencing both tumour size and the likelihood of metastatic deposits. The 5 year disease free rate is approximately 70% in early oral cancer, falling to less than 30% in more advanced cases. Furthermore, aetiological factors associated with tongue cancer (primarily smoking and alcohol) render survival worse for patients than for other malignancies. The “field cancerisation” concept means that they are at increased risk of developing second primary oral tumours in the head and neck region, as well as being at significant risk from cardiovascular and liver disease associated with their lifestyle.

How is Oral Cancer (Squamous Cell Carcinoma of the Floor of the Mouth) Treated?

Treatment of oral cancer revolves around a combination of surgery and radiotherapy. Lesions should be treated surgically where possible because of the risks of bone necrosis with radiotherapy. Excision can be very difficult due to the proximity of the mandible. Where surgery is not possible, radiotherapy can be used – either with curative intent or for palliation. Post-operative radiotherapy may also be used. Bleomycin and cisplatin have both been used in the treatment of oral cancer. Improvement in oral cancer symptoms is an important measurement. Specific monitoring may be by thorough serial inspection of the head and neck region – looking for oral cancer recurrence as well as second primary oral tumours. Ideally this would include pan- /triple-endoscopy. There are no specific screening recommendations at the moment but several clinical trials are currently being undertaken into the benefit of different screening techniques. The oral cancer symptoms that may require attention are somatic pain from bone metastases, visceral pain from liver or lung metastases and neurogenic pain if nerve tissue is compressed. Coughing and breathlessness from lung involvement may require specific treatment.