Medical student Ritianne Buhagiar details the possible causes of oral cancer and how to detect the symptoms. The good news is that it can be prevented, especially by quitting smoking and limiting alcohol consumption.
Oral cancer, colloquially known as ‘mouth cancer’, is an abnormal (malignant) growth of body cells in the mouth. It may develop in any part of the oral cavity, but it mainly develops in the tongue, floor of the mouth, mucosa of the cheeks, gums and the hard and soft palates.
More than 90 per cent of oral cancers begin in the flat epithelial cells (cells that help protect or enclose organs; some produce mucus or other secretions) that line the surfaces of the mouth, tongue and lips. These cancers are called squamous cell carcinomas. However, there are other types of oral cancers that may manifest in the oral cavity such as minor salivary gland tumours and metastases from cancers in other parts of the body.
Alcohol is the second main cause of oral cancer.Causes
It is generally accepted that oral cancer is the result of a multistep process of accumulated genetic alterations. These alterations affect what is called epithelial cell behaviour, leading to a series of events that ultimately progress to invasive squamous cell carcinoma. The most frequent predisposing factors responsible for these genetic alterations are chronic irritation and inflammation.
In the Western world, this is mainly due to alcohol consumption (70 per cent of people diagnosed with oral cancer are heavy drinkers) and excessive tobacco use (80 per cent of those with oral cancer smoke).
Exposure to sunlight may also increase the risk of lip cancer, most often on the lower lip. Occasionally, there might be a chronic traumatic ulcer that turns malignant. Some studies suggest that being infected with the human papillomavirus (HPV) may increase the risk of oral cancer.
Precancerous lesions of oral mucosa, also known as potentially malignant disorders, consist of a group of diseases which should be diagnosed in the early stage. The term ‘precancerous’ is applied to an abnormal type of mucous membrane that is more likely to undergo cancerous change. The commonest precancerous condition is leukoplakia.
Leukoplakia is a white patch on the mucosa, which cannot be scraped off. It is important to highlight that while not all white patches are dangerous, they all need attention, particularly those in the danger areas of the mouth.
Another condition, erythroplakia, is a velvety red or a red and white speckled area, flat or slightly raised, that often bleeds when scraped. Lichen planus, particularly in its erosive form, is also a precancerous condition.
As with all cancers, oral cancer may spread and squamous cell carcinoma is prone to metastasis, characteristically to the lymph nodes in the neck, in the early stages. Cancer can also metastasise from the oral cavity or oropharynx to the parotid gland or upper digestive tract.
Detection
In order to detect oral cancers, dental professionals must examine the entire oral cavity both visually and manually as well as inspect and palpate the lymph nodes of the neck and the danger area of the mouth. The latter includes the posterolateral margins of the tongue and the floor of the mouth, which is the area that is more prone to malignant change than the rest of the oral mucosa.
Oral cancer often appears as a painless non-healing sore in the mouth or on the lips
Oral cancer often appears as a painless non-healing sore in the mouth or on the lips. Cancer should also be suspected in case of any oral ulceration, with no obvious cause, that does not resolve within two to three weeks. Precancerous conditions, as explained above, may also progress to cancer.
Other possible symptoms include unexplained bleeding in the mouth, sudden loosening of teeth, swallowing problems, lumps or bumps on the neck, and earaches.
Investigations
Oral cancer is diagnosed by the patient’s history and physical examination but is established by a biopsy of oral tissue.
An incisional biopsy is commonly used but an oral brush biopsy is now attainable, particularly in cases of widespread, potentially- cancerous lesions.
Occasionally, jaw and chest radiography, endoscopy, complete blood cell count and liver function tests may also be indicated to confirm the diagnosis and to determine whether the cancer has metastasised, mainly to cervical lymph nodes. CT or MRI scans can determine the extent and invasion of the tumour and if any of the cervical lymph nodes are involved.
Management
The aim of oral cancer treatment is to eliminate the tumour, to restore the structure and function of the affected area and to prevent subsequent relapse. In cases of incurable disease, the objective changes to improving the quality of patients’ life.
The first step in management should always be prevention. This can be done educating the public about the importance of quitting smoking and limiting alcohol consumption. Regular dental check-ups will help detect any suspicious lesions.
For malignant tumours of the oral cavity, surgical removal has always been the most important procedure for treatment. Surgery can also be used in cases of radiotherapy-resistant tumours. Surgery to the face and mouth, however, may affect the quality of life and is potentially disfiguring.
Radiotherapy is usually used with surgery or chemotherapy in order to kill cancer cells. This kind of therapy, like every other, has its advantages and disadvantages.
With radiotherapy, normal anatomy and function are maintained, general anaesthesia is not needed, and surgery is still available if radiotherapy fails.
Radiotherapy, however, has side effects. There may be painful inflammation of the mouth linings, known as mucositis and a reduction in the amount of saliva produced, as the glands in the line of the radiation beam are also killed off.
The lack of saliva worsens the mucositis and gives a dry mouth. This in turn may result in difficulty in swallowing and also leads to an increase in tooth decay and periodontal disease, as the protective effects of saliva are lost. The parts of the face that are irradiated may become stiff and fibrous. This may cause complications if surgery is required later on.
The mucositis may be helped with painkillers, anaesthetic gels and mouthwashes. Salivary stimulants and artificial saliva help with the dry mouth but it is important that all dental disease is controlled before radiotherapy, as it is very difficult to do so afterwards.
For early-stage oral cancer, radiation therapy alone has been found to achieve similar success rates to surgery. For more advanced cases, radiotherapy is not commonly used alone, unless the tumour site is inoperable, or if the patient chooses not to have surgery. It can also be given as a palliative treatment option for more advanced and terminal cases.
With a continuing worldwide increase in the number of patients diagnosed with oral cancer year after year, it is now considered an important health issue. Oral cancer is characterised by poor prognosis and a low survival rate despite sophisticated surgical and radiotherapeutic treatment.
Hence, oral cancer prevention should always be taken seriously and as previously alluded to, can be accomplished by worthwhile lifestyle modifications, that is, cutting down on smoking and alcohol intake. Last but not least, regular dental check-ups are of vital importance since the dental surgeon is the person best positioned to detect this type of cancer. Early detection saves lives.
The article was reviewed by Simon Camilleri, a senior lecturer at the University of Malta.