Merck Manual

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Mouth and Throat Cancer

(Oral Cancer; Oropharyngeal Cancer)

By

Bradley A. Schiff

, MD, Montefiore Medical Center, The University Hospital of Albert Einstein College of Medicine

Last full review/revision Feb 2020| Content last modified Feb 2020
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Mouth and throat cancers are cancers that originate on the lips, the roof, sides, or floor of the mouth, tongue, tonsils, or back of the throat.

  • Mouth and throat cancers may look like open sores, growths, 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 used to determine the size of the cancer and how far the cancer has spread.

  • Treatment depends on the location, size, and extent of spread of the cancer and may include surgery, radiation therapy, and chemotherapy.

In 2019, mouth and throat cancer is estimated to develop in about 53,000 people in the United States, resulting in about 10,860 deaths, mostly in men older than 50.

Types of cancer found in the mouth and throat

Squamous cell carcinoma, which means the cancer develops in the squamous cells that line the inside of the mouth or throat, is by far the most common type of oral cancer. Other types of cancer, such as verrucous (warty) carcinoma, malignant melanoma, and Kaposi sarcoma, are much less common.

Risk Factors

The main risk factors for mouth and throat cancer are

  • Tobacco use

  • Alcohol use

  • Human papillomavirus (HPV) infection

Tobacco use causes many mouth and throat cancers. Tobacco use includes smoking cigarettes, cigars, or pipes; chewing tobacco or chewing betel quid (a mixture of substances that includes tobacco, also called paan); and dipping snuff. In the United States, smoking cigarettes (particularly more than 2 packs per day) is the main tobacco-related risk factor for mouth and throat cancer. Cigar smoking can also increase risk. Pipe smoking increases risk of cancer in the part of the lips that touch the pipe stem. Chewing tobacco or snuff increases the risk of developing cancer in the cheeks, gums, and inner surface of the lips, where the tobacco has the most contact, by 50%.

Chronic or heavy alcohol use also increases the risk of mouth and throat cancer. The increase in risk is proportional to the amount of alcohol consumed. 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 greatest risk results from the combined heavy use of both tobacco and alcohol, which is two to three times 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 30-fold. People who continue to use tobacco and alcohol after developing mouth or throat cancer have more than twice the chance as the rest of the population of developing a second mouth or throat cancer.

Human papillomavirus (HPV), the virus that causes genital warts and may infect the mouth during oral sex, is associated with the development of mouth and throat cancer. HPV-associated mouth and throat cancer is increasing, mainly among younger people in North America and northern Europe. HPV infection raises the risk of throat cancer 16-fold, and HPV causes 60% of throat cancers. The number of sex partners and frequency of oral sex are important risk factors. Certain strains of this virus predispose people to throat cancer and, to a lesser extent, mouth cancer.

Because more people are being vaccinated against HPV, throat cancers caused by HPV are expected to become less common in the future. However, because throat cancer does not develop for many years, the decrease will take years to become evident.

Gender is a risk factor. About three quarters of mouth and throat cancers occur in men.

Increasing age, as with most cancers, increases risk.

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, and poor oral hygiene are also risk factors. Heavy sun exposure can cause cancer of the lip.

Symptoms

Symptoms of mouth and throat cancer 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 be 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 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

  • Endoscopy

  • Biopsy

  • Imaging tests for staging

To diagnose mouth and throat cancers, 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 to determine the extent (stage) of the cancer, such as

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. Doctors also use an endoscope to look down into the mouth and throat to see cancer in nearby structures. Doctors do laryngoscopy (to see inside the larynx), bronchoscopy (to see inside the airways), and esophagoscopy (to see inside the esophagus).

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 for people with mouth and throat cancer vary, depending on

  • The original location of the tumor

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

  • The cause

The cure rate for squamous cell carcinoma of the mouth 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 75% 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 75% 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 half. 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.

On average, 60% of people who have throat cancer survive at least 5 years after the diagnosis. Rates are more than 75% if the cause is human papillomavirus (HPV) and less than 50% if the cause is something else.

People who have cancer caused by HPV 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 mouth and throat 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.

Current vaccines against HPV target some of the HPV strains that cause throat cancers, so vaccination may prevent some of these cancers from developing.

Treatment

  • Surgery

  • Radiation therapy, sometimes combined with chemotherapy (chemoradiation)

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. Speech and swallowing therapy may be needed after significant surgeries. Radiation or chemoradiation is given after surgery if the cancer is advanced.

For people who cannot have surgery, radiation therapy is an alternative first treatment. Chemotherapy is not usually used as initial treatment but is recommended in addition to radiation therapy for people whose cancer has spread to many lymph nodes.

For throat cancer, doctors use surgery more often as the first treatment for throat cancer. Newer techniques allow doctors to operate through the mouth rather than through an incision in the neck. 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, or sometimes chemoradiation, can be used either after surgery or as first treatment. Traditionally, doctors have used radiation therapy for early-stage cancers 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.

Side effects of treatment

Radiation therapy to the mouth and throat causes many side effects including

  • Destruction of the salivary glands, which leaves the person's mouth dry and can lead to cavities and other dental problems

  • Poor ability of the jawbones to heal from dental problems or injury

  • Osteoradionecrosis, a loss of bone and surrounding soft tissue in the radiated area

Because of these side effects, all pre-existing 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.

Likewise, good dental hygiene is critical for people after radiation therapy, because after radiation exposure, the mouth will heal 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.

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