Oral cancer

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Oral cancer, sometimes referred to as oropharyngeal cancer, is a malignancy that involves the tissues of the mouth (oral cavity), such as the lips, gums, palate and tongue, or the upper part of the throat (oropharynx).

Oral cancer often starts with the squamous cells of the mouth (squamous cell carcinoma), appearing as whitish or reddish spots on the surface. Leukoplakia, a whitish patch on the membrane of the oral cavity, develops. With time and progression, the cancer cells can penetrate deeper into tissues.

Contents

Prevalence

Oral cancer is the eighth leading cancer in the world, affecting older individuals from age 50, and more men than women. It is more common in developing countries, with 58% of all global cases coming from Asia, according to the World Health Organization (WHO).

In the Philippines, cancer of the oral cavity was the 9th leading cancer among males and females from 1995 to 1998. The incidence rate was at 6.8 per 100,000 population.

Causes and risk factors

Globally, tobacco use and excessive alcoholic intake account for ninety percent (90%) of all cases of oral cancer. Tobacco use, whether smoked or chewed (also called smokeless tobacco), remains to be the single most important and preventable risk factor for oral cancer.

In the Philippines, the habits of chewing betel nuts and inverted smoking (smoking with the lit-end of the cigarette inside the mouth) have been associated with oral cancer.

In 1985, a study by the International Agency for Research on Cancer concluded that “there is sufficient evidence that the habit of chewing betel quid containing tobacco is carcinogenic to humans.” However, chewing betel quid without tobacco was not sufficiently proven to cause oral cancer.

An emerging risk factor, especially among younger age groups (below age 50), is HPV16 (human papillomavirus 16), which is sexually transmitted. HPV16 causes 90% of cervical cancers.

Excessive sun exposure has been associated with lip cancer.

A diet low in beta-carotene and Vitamin C is linked to some cancers including oral cancer. There is little evidence that dental factors, such as poor oral hygiene, ill-fitting dentures or misaligned teeth, can cause oral cancer.

Symptoms

Oral cancer may go unnoticed, being painless most of the time in the initial stages. It starts as red or white spots in the oral mucosa, or may appear as a common mouth sore. Unlike benign mouth sores, the lesion does not heal within fourteen days.

Other symptoms include:

  • Difficulty in swallowing, chewing or speaking
  • Lump or mass in the mouth or neck
  • Persistent hoarseness of voice
  • Bleeding in the mouth (characterized by blood in saliva or sputum)
  • Earaches, usually one-sided (unilateral)
  • Numbness around the mouth or face

Diagnosis

A biopsy is done to take a sample of suspicious tissues from the oral cavity for histopathological studies. Dental x-rays and endoscopy are also performed. Other imaging studies, such as magnetic resonance imaging (MRI), computed tomography (CT) or ultrasound scans, may also be done to check involvement of other organs, because cancers of the lungs, esophagus, head or neck frequently occur along with oral cancer in the elderly (synchronous malignancies).

Treatment

Surgical removal of cancerous tissues as well as the lymph nodes of the neck is commonly done in oral cancer. Surgical reconstruction may be performed when there is severe disfigurement of face, and in cases where functions such as speaking, chewing, and swallowing are impaired.

Radiation therapy, chemotherapy or both may be done after surgery, depending on the stage of cancer. Intensity Modulated Radiation Therapy (IMRT) is a safer option wherein radiation of varying intensities is used to target cancer cells while keeping exposure of healthy cells at minimum.

Prior to radiation therapy, the cancer patient may be given radiosensitizers orally or intravenously which will make cancer cells more receptive to radiation.

Oral cancer treatment affects dental health, often leading to injured gums or oral cavity tissues. Preventive measures like oral prophylaxis, flouride treatment, and denture checks are done two weeks before radiation therapy to minimize adverse effects.

Post-treatment care

The oral cancer patient must be advised on the possible side effects of treatment such as mouth sores, dryness of mouth, and impaired taste. Proper oral care practices and regular dental visits are important.

In many cases, speech will be affected and the patient may need to undergo speech therapy with a speech pathologist to be able to cope with speaking difficulties.

Impairment of swallowing (dysphagia) is also significant, and must be recognized early to avoid choking accidents.

As with other cancers, regular follow-up with the oncologist is recommended and usually consists of thorough physical examination, imaging studies and blood tests.

Survival

Along with colon and breast cancers, the five-year survival rate for oral cancer in the Philippines exceeds 40%, especially with early detection and treatment. However, in advanced stages where malignancy has metastasized to other organs, the five-year survival rate drops to 20%.

Prevention

Chewing betel nut and tobacco should be avoided in order to reduce the risk of developing oral cancer. Public awareness campaigns must be geared especially towards rural areas where betel nut chewing is still widely practiced.

Cessation of smoking and of excessive alcoholic intake is an important step in preventing many diseases, including oral cancer.

Regular dental checks is recommended for everyone, but should be highly encouraged among smokers, alcoholic drinkers and those who practice betel nut chewing in order to screen oral mucosal growths in the early stages.

References