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Mouth and Throat Cancer

(Oral Cancer; Oropharyngeal Cancer)

by Bradley A. Schiff, MD

  • Mouth and throat cancers may look like open sores or discolored areas in the mouth.

  • Doctors do biopsies to diagnose mouth and throat cancers.

  • Imaging tests, such as computed tomography, magnetic resonance imaging, and positron emission tomography, are done to see how far the cancer has spread.

  • Treatment is usually with surgery and radiation therapy.

Mouth and throat cancers include cancers that occur on the lips, the roof, sides or floor of the mouth, the tongue, the tonsils, or the back of the throat. Cancer of the voice box (larynx) is termed laryngeal cancer (see Laryngeal Cancer). Each year, mouth and throat cancer develops in about 41,000 people in the United States and causes 8,000 deaths, mostly in people older than 50.

Types of cancer

Squamous cell carcinoma is by far the most common type of oral cancer.

Other types of cancer, such as verrucous (warty) carcinoma, malignant melanoma (see Melanoma), and Kaposi sarcoma (see Kaposi Sarcoma), are much less common. Verrucous carcinoma appears as a white grooved surface on the lining of the mouth (mucosa). Malignant melanoma is usually associated with a history of sunburns and occurs on the lips. However, it occasionally occurs inside the mouth, most commonly on the roof of the mouth. Kaposi sarcoma is a cancer of the blood vessels near the skin and in the lining of the mouth and throat. In people with AIDS, when Kaposi sarcoma occurs in the mouth, it usually occurs on the roof of the mouth. The tumor is usually blue or purple and is slightly raised.

Risk Factors

The main risk factors for mouth and throat cancer are

  • Tobacco use

  • Alcohol use

  • Human papillomavirus (HPV) infection

Tobacco use —including smoking cigarettes (particularly more than 2 packs per day), cigars, or pipes; chewing tobacco or chewing betel quid (a mixture of substances that includes tobacco, also called paan); and dipping snuff—causes many mouth and throat cancers. Cigars and cigarettes are equally dangerous as risk factors, followed in descending order by pipe smoking and chewing tobacco.

Chronic or heavy alcohol use also increases the risk of mouth and throat cancer. Risk increases dramatically when alcohol use exceeds 6 ounces of distilled liquor, 15 ounces of wine, or 36 ounces of beer per day. There is some evidence that the alcohol contained in mouthwash can contribute to oral cancer when used repeatedly over a long period of time.

The combination of heavy use of both tobacco and alcohol is more likely to cause cancer than either one alone. Such combined use raises the risk of mouth cancer 100-fold in women and 38-fold in men; it raises the risk of throat cancer 21-fold. People who continue to use tobacco and alcohol after developing mouth and throat cancer have more than twice the chance as the rest of the population of developing a second mouth and throat cancer.

HPV, which is becoming more and more common a risk factor, causes genital warts (see Genital Warts (Human Papillomavirus Infection, or HPV Infection)) and may infect the mouth during oral sex. Certain strains of this virus predispose people to throat cancer and, to a lesser extent, mouth cancer.

Gender is a risk factor. About two thirds of mouth and throat cancers occur in men, but increased tobacco use and increased rate of HPV infection among women over the past few decades is gradually closing the gender gap. As with most cancers, risk increases with age.

Other factors that add to the risk of mouth cancer include repeated irritation from the sharp edges of broken teeth, fillings, cavities, or ill-fitting dental prostheses (such as dentures). Previous x-rays of the head and neck, chronic candidiasis (see Candidiasis), and poor oral hygiene are also risk factors. Heavy sun exposure can cause cancer of the lip.

Did You Know...

  • The greatest controllable risk factors for oral cancer are tobacco use and alcohol use.

Symptoms

Symptoms vary somewhat depending on where the cancer is located.

Mouth cancer is usually painless for a considerable length of time but eventually causes pain as the cancer grows. When pain begins, it usually occurs with swallowing, as with a sore throat. People may have difficulty speaking. Squamous cell carcinomas of the mouth often look like open sores (ulcers) and tend to grow into the underlying tissues. The sores may look like erythroplakia or leukoplakia (see Precancerous changes), which are flat or slightly raised patches colored red (erythroplakia) or white (leukoplakia). Cancers of the lip and other parts of the mouth often feel rock hard and are attached to the underlying tissues. Most noncancerous lumps in these areas are freely movable. Discolored areas on the gums, tongue, or lining of the mouth also may be signs of cancer. An area in the mouth that has recently become brown or darkly discolored may be a melanoma. Sometimes a brown, flat, freckle-like area (smoker's patch) develops at the site where a cigarette or pipe is habitually held between the lips.

Throat cancer typically causes throat pain that increases with swallowing, difficulty swallowing and speaking, and sometimes ear pain. Sometimes, a lump in the neck is the first sign of throat cancer.

In most types of mouth and throat cancer, once symptoms make it difficult to eat, people begin to lose weight.

Diagnosis

Doctors do a biopsy (removal of a tissue specimen for examination under a microscope) of any abnormal area seen during the examination. Only a biopsy can determine whether a suspicious area is cancerous. If doctors do not see an abnormal growth in the mouth of people who have symptoms, they examine the throat using a special mirror and/or a flexible viewing tube (endoscope). They do a biopsy of any abnormal areas seen during this examination.

If the biopsy shows cancer, doctors then do imaging tests, such as computed tomography (CT), magnetic resonance imaging (MRI), or a combination of positron emission tomography (PET) and CT. These imaging tests are done to help doctors determine the size and location of the cancer, whether it has spread to nearby structures, and whether it has spread to lymph nodes in the neck. People who have squamous cell carcinoma also undergo endoscopy to look for cancer in nearby structures. Doctors usually do laryngoscopy (examination of the larynx), bronchoscopy (examination of the lungs), and esophagoscopy (examination of the esophagus). These areas are evaluated because the risk of additional cancers being present is up to 10%.

Screening

Because early detection vastly improves the likelihood of cure, doctors and dentists should thoroughly examine the mouth and throat during each routine medical and dental examination. The examination should include the area under the tongue, where people typically do not see or feel an abnormal growth until it has become quite large.

Prognosis

The survival rates vary greatly depending on

  • The original location of the tumor

  • Whether and how far it has spread (the stage)

  • The cause (to some extent)

The cure rate for squamous cell carcinoma is high if the entire cancer and the surrounding normal tissue are removed before the cancer has spread to the lymph nodes. On average, more than 50% of people who have carcinoma of the tongue that has not spread to the lymph nodes survive at least 5 years after the diagnosis. About 65% of people who have carcinoma of the floor of the mouth that has not spread survive at least 5 years after the diagnosis. However, if the cancer has spread to lymph nodes, the 5-year survival rate decreases by about 50%. Regrettably, cure rates for squamous cell carcinoma have not improved much over the past several decades. However, verrucous carcinoma is rarely fatal because it develops late in life and grows slowly. About 90% of people with carcinoma of the lower lip survive at least 5 years, and the carcinoma rarely spreads. Carcinoma of the upper lip tends to be more aggressive and spreads.

People who have cancer caused by the HPV virus have a better survival rate than people with a similar cancer caused by other factors.

Prevention

Avoiding excessive alcohol and tobacco use can greatly reduce the risk of most oral cancers. Smoothing rough edges from broken teeth or fillings is another preventive measure. Staying out of the sun and using sunscreen help reduce the risk of lip cancer. If sun damage covers a large area of the lip, a lip shave, in which the entire outer surface is removed using either surgery or a laser, may prevent a progression to cancer.

Treatment

The mainstays of treatment for mouth and throat cancer are surgery and radiation therapy. Doctors select the treatment based on the size and location of the cancer.

For mouth cancer, surgery is usually the first treatment. Doctors remove the cancer and sometimes also remove the lymph nodes under and behind the jaw and along the neck. Consequently, surgery for mouth cancers can be disfiguring and psychologically traumatic. Newer reconstructive surgery techniques done during the initial surgery can improve function and help restore normal appearance. Missing teeth and jaw parts can be replaced with prosthetic devices. People who cannot have surgery and people whose cancer has spread to many lymph nodes may be treated with radiation therapy. Chemotherapy is not usually used unless the cancer has spread widely, in which case it may help relieve symptoms.

For throat cancer, doctors have typically used radiation therapy and have added chemotherapy when cancer was more advanced. A specific type of radiation therapy called intensity-modulated radiation therapy (IMRT) allows doctors to deliver the radiation to a very specific area, which may decrease side effects. Recently, doctors have begun using surgery more often as the first treatment for throat cancer. Newer techniques that allow doctors to operate through the mouth rather than through an incision in the neck seem useful. Some techniques use an endoscope to guide laser surgery. Another technique involves use of a surgical robot. The surgeon controls the arms of the robot from a console and views the operation via a camera attached to an endoscope that has been inserted into the person's mouth.

Radiation therapy to the mouth and throat causes many side effects and often destroys the salivary glands. Destruction of the salivary glands leaves the person's mouth dry, which can lead to cavities and other dental problems. If the salivary glands have not been destroyed, saliva production usually recovers several weeks after the radiation treatment is completed. Because jawbones exposed to radiation do not heal well, dental problems should be completely treated before radiation is given. Any teeth likely to become problematic are removed, and time is allowed for healing before radiation is given.

Good dental hygiene is critical for people who have had radiation therapy for mouth and throat cancer because the mouth heals poorly if dental surgery, such as tooth extractions, is ever needed. Such hygiene includes regular examinations and thorough home care, including daily home fluoride applications. If the person eventually has a tooth pulled, hyperbaric oxygen therapy may help the jaw heal without causing osteoradionecrosis. Osteoradionecrosis is the loss of bone and surrounding soft tissue in an area of the head or neck that has been treated with radiation.

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