Oral cancer ; Important facts

There are several type of oral cancers and the most common type is oral squamous cell carcinoma which is a malignant neoplasm which arises from the oral epithelium. It may affect the lips as well as intraoral sites.

oral cancer

Important facts about oral squamous cell carcinoma (SCC) 

oral carcinoma

• There are 4400 new cases of oral cancer every year in the UK (Cancer Research UK).
• Men are affected more than women but the incidence in women is rising.
• The most commonly affected sites are the lateral border of the tongue, floor of mouth and the retromolar region and about 80% of cancers in the Western world occur in these sites.

• This is related to alcohol consumption and smoking, two important risk factors in the development of oral cancer. It is thought that the carcinogens (chemicals that cause cancer) which are present in tobacco dissolve in saliva and pool in these regions of the mouth.

• Alcohol itself is not carcinogenic (i.e. it does not contain carcinogens) but it potentiates the effects of carcinogens by increasing the permeability of the oral mucosa.

lip cancer

• Cancer on the lower lip is caused by sunlight and is prevalent in fair-skinned individuals with outdoor occupations or lifestyles.

• A diet low in fresh fruit and vegetables is a risk factor for the development of oral cancer.

• The percentage of people who survive 5 years after diagnosis of oral cancer (all sites) is in the region of 50%.
• In South-East Asia many cases of oral cancer are caused by betel quid chewing and occur on the cheeks adjacent to where the quid is placed. Studies have shown that immigrant populations from South-East Asia in the UK continue this habit and have a higher risk of developing oral cancer (Farrand et al., 2001;Warnakulasuriya, 2002).

• Almost all patients with cancer of the lip survive 5 years.

• The percentage of people who survive 5 years with cancer of the posterior parts of the mouth is very low.
• The majority of new cases occur in individuals over the age of 40 years with a peak incidence between 60 and 70 years.
• The incidence is rising in younger individuals. It is thought this is due to changes in alcohol consumption rather than an increase in tobacco consumption (Hindle et al., 2000) but one study has shown that a significant proportion of young patients have no risk factors (Llewellyn et al., 2003).

Pathology of oral cancer

In health the oral epithelium forms a continuous layer on the surface of the mucosa but in oral cancer the epithelium proliferates excessively due to genetic changes and eventually the epithelial cells grow down into the underlying connective tissue. This is known as invasion and is a characteristic feature of malignancy . The tumour cells continue to divide and invade and will spread into and destroy the underlying tissues which will then feel hard and not function properly. Tissues affected in this way may include skeletal muscle, salivary glands and bone. Tumour cells will also invade lymphatic vessels and spread to the cervical lymph nodes in the neck. This process is called metastasis.

Once in the node, the tumour cells continue to proliferate and they destroy the node and sometimes spread out into the tissues of the neck. Nodes which contain tumour feel very hard and are usually painless. If the tumour has spread into the neck, the node will not be mobile, as is usual, but will be attached (fixed) to the surrounding tissues. In a small proportion of cases the cancer spreads beyond the lymph nodes, enters the blood stream and grows in other organs, but this is rare.

Clinical features of oral cancer

• Recognition of oral cancer is important and early detection,particularly before the cancer has spread to the lymph nodes in the neck, may save lives. 

Important features of oral cancers

• Some oral cancers arise in pre-existing leukoplakia; lesions which have a raised nodular surface and show variations in colour with speckled red–white areas are particularly suspicious.
• Some cancers present as erythroplakia. These are velvety red patches which may be raised above the surrounding tissues .
• Long-standing ulceration is also a common presentation and typically the ulcers have raised, rolled margins.
• Some cancers fungate (grow out) into the oral cavity as well as invade into the underlying tissues.
• The site of the lesion is important; high-risk sites are the lateral border of tongue, the floor of mouth and the retromolar area.
• Tissues affected by oral cancer are firm or hard to touch and there may be destruction leading to loss of function.
• Lesions are usually painless in the early stages and many patients are unaware of the lesions until they are quite large.
• If the cancer has spread to the cervical lymph nodes these will feel rock hard and painless and may be enlarged.
• In advanced stage disease the patient may appear very thin and pale (cachexic).

Treatment

• The diagnosis of oral cancer is made by biopsy and histopathological examination. Once the diagnosis is made it is important for the clinician to determine the extent of the disease and whether it has spread to the lymph nodes in the neck. 
• Oral cancer is treated by surgery and/or radiotherapy, and the decision as to which is appropriate is taken at multi-disciplinary team meetings attended by all who are involved in patient care.