Oral Cancers – Causes, Signs and symptoms

Oral Cancers

Also called: Oral Cavity Cancers, Lip Cancers, Mouth Cancers

Reviewed By:
Mark Oren, M.D., FACP

Summary

Oral cancers, also known as lip and mouth cancers, are a group of diseases in which malignant cells are found in the tissues of the lip and mouth. The mouth or oral cavity includes the lips, inside of the mouth, gums, teeth and tongue.

Most oral cancers damage the squamous cells that line the inside of the mouth. The most common symptoms of oral cancers include a sore or pain in the mouth that does not go away or a white or red patch in the mouth or pain in the mouth. A lump or thickened area on the lips, gums or in the mouth also may be a symptom of oral cancer.

Oral cancers are strongly linked to tobacco use, including cigarette and cigar smoking, as well as smokeless (chewing and snuff) tobacco. In addition, individuals who consume high amounts of alcohol are at higher risk of the disease. Frequent or extended exposure to the sun is one of the highest risk factors for lip cancers. Studies have also shown that certain types of human papillomavirus (HPV) may be associated with the development of oral and oropharyngeal cancers.

Oral and pharyngeal cancers are the ninth most common cancer among men in the United States, according to the American Cancer Society. Men, especially over the age of 40 years and blacks have the greatest risk of developing oral cancers.

A physical examination of the lips and mouth may initially detect abnormal and potentially cancerous areas. Samples of tissue from the suspected areas will be collected and examined under a microscope. If the cells are abnormal, a biopsy will be performed to determine the presence and type of cancer. Additional tests may be completed to determine if the cancer has spread (metastasized) to other areas, such as the larynx or lymph nodes.

Treatments for oral cancers include surgery, radiation therapy and chemotherapy. These treatments may be used alone or in a combination depending on the type, location and stage of the cancer. Oral cancers usually can be cured with early detection and proper treatment. Individuals who have had oral cancers, however, have a high risk of developing a secondary cancer in the surrounding area.

The best way to prevent oral cancers is to reduce or eliminate the major risk factors associated with the disease. Not smoking or drinking excessively greatly reduces the chances of developing oral cancers. In addition, it may prevent the cancers from recurring in the future.

About oral cancers

Cancer of the oral cavity occurs when malignant tumors are found in the tissues of the lip or mouth.  More than 90 percent of cancers of the oral cavity occur in the squamous cells that line the mucosal surfaces in the mouth and throat. In the oral cavity, these include the:

  • Lips
  • Inside lining of the cheek (buccal mucosa)
  • Front two–thirds of the tongue
  • Floor of the mouth
  • Upper and lower gums (gingiva)
  • Bony roof of the mouth (hard palate)
  • Area behind the wisdom teeth (retromolar trigone)

Cancer cells develop because of damaged DNA, the genetic code that controls how cells behave. In most cases, when the DNA becomes damaged, the body is able to repair it. In cancer cells, the DNA is not repaired and the abnormal cells grow out of control. 

There are many types of tissues in the oral cavity composed of a variety of cells. Different types of cancer can develop from each kind of cell.  Most oral cancers start in the squamous cells, which are flat, scale–like cells that line the oral cavity. For this reason, oral cancer is often called squamous cell carcinoma. The type of cancer that develops is important as it determines the plan of treatment and the outlook for recovery.

Many types of tumors can develop as the result of oral cancers, and many of them are not malignant. Tumors that are benign do not spread to other tissues or parts of the body. Cancerous tumors, however, can penetrate the surrounding tissues and metastasize to other parts of the body. If lip and mouth cancers are not treated, they can spread to the:

  • Pharynx. Tube that is part of the digestive tract and runs behind the nasal cavities, mouth and larynx.

  • Larynx (voice box). Cartilage in the throat that houses the vocal cords. It connects to the lower pharynx.

  • Esophagus. Tube that extends from the lower pharynx to the stomach. Food passes from the mouth through the pharynx and into the stomach.

  • Thyroid gland. Located in the front of the neck, this gland contributes to hormone production.

Oral cancers occur more often in African Americans than whites and men have twice the risk than women. Men over the age of 40 are also at higher risk. More than half of all patients diagnosed with oral and oropharyngeal cancer are over the age of 65. Researchers believe the higher incidence of oral cancer cases in older individuals and males is linked to increased tobacco and alcohol use with these populations.

The number of new cases of oral cancer has been declining during the past 30 years. According to the Surveillance Epidemiology and End Results (SEER) cancer review published by the National Institutes of Health (NIH), the incidence of oral and oropharyngeal cancer in the United States dropped 1.8 percent between 1981 and 2004. In addition, the death rate for oral and oropharyngeal cancer decreased significantly since the late 1970s, with the fastest decline in the 1990s.

The American Cancer Society (ACS) estimates that 34,360 cases of oral and oropharyngeal cancer will be diagnosed in the United States in 2007. About half of these cancers will develop on the tongue and lips. Cancers on the floor of the mouth and in the minor salivary glands account for another 25 percent of these cancers. The remaining cancers are diagnosed in the gums and other areas of the mouth. The ACS estimates that about 7,500 people will dies of oral cancers in 2007.

Survival rates vary according to the stage of the cancer. As with other forms of cancer, survival is highest when the disease is caught early. The ACS reports the survival rates for all stages of oral and oropharyngeal cancer combined as follows:

Survival Rates%
One–year84
Five–year (all stages)59
Ten–year (all stages)48

The five–year survival rate refers to the number of people who will live five years after their cancer is diagnosed. Many people will live much longer than five years, especially if the cancer is detected early and has not spread to the lymph nodes.

Patients with oral cancer are also at greater risk of developing another form of cancer. Newly diagnosed patients have a 15 percent risk of having another cancer in a nearby area, such as the throat or esophagus. In addition, 10 to 40 percent of patients cured of oral or oropharyngeal cancer will develop a second oral cancer or cancer in nearby tissues later in life, according to ACS. Individuals who are diagnosed with oral cancers need to avoid known risk factors (e.g., tobacco use, alcohol) and need to be monitored throughout their lives.

Types and differences of oral cancers

There are many types of tumors that can develop on the lips or in the mouth. Oral cancers are categorized by where the cancer occurs in the oral cavity. They include the following:

  • Lip cancer. Occur far more commonly in men than women. Most lip malignancies are squamous cell cancers. People with light skin or with prolonged sun exposure are more prone to develop lip cancers.
  • Cancers of the floor of the mouth. The floor of the mouth is U–shaped and bounded by the lower gum and the tongue. Cancers in this area are usually malignancy cell cancers and typically occur in the front, middle area of the mouth.
  • Tongue. Almost all tongue malignancies are squamous cell cancers, usually occurring on the side or the underside of the tongue. A condition called leukoplakia (formation of white patches) is common on the tongue. 
  • Cancer of the cheek. The lining of the inside of the cheek (buccal mucosa) is a rare site for oral cancer, especially in the United States. It is common in countries where people chew tobacco mixed with betel leaves, areca nut and lime shell.
  • Gum (gingiva) and hard palate cancers. Cancers of the lower gum are usually squamous cell cancers. In the upper gum and hard palate area (including behind the wisdom teeth), cancers in these areas can be squamous cell or some other type of cancer.
  • Minor salivary gland cancer. This cancer can develop in the glands that are located throughout the mucosal lining of the mouth and throat. There are several types of salivary gland cancer, including:
    • Adenoid cystic carcinoma
    • Mucoepidermoid carcinoma
    • Polymorphous low–grade adenocarcinoma

Risk factors and causes of oral cancers

Physicians cannot clearly state the cause of lip and mouth cancers but there are several associated risk factors. These types of cancer appear to be the result of elements that damage the cells in the oral cavity.  The damage may cause the cells to malfunction and rapidly reproduce as cancer cells.

There are several risk factors linked to the growth of cancerous cells in the oral cavity. Tobacco use is the strongest link to lip and mouth cancers. Research has shown that tobacco causes damage to cells in the lining of the mouth, pharynx and larynx. Cells must grow more rapidly to repair this damage. Many of the chemicals found in tobacco cause damage to DNA, which tells the cells how to grow and repair the damage. In essence, tobacco not only damages cells but also inhibits the ability to grow new ones.

The American Cancer Society (ACS) estimates that approximately 90 percent of people with oral or throat cancer use tobacco. The risk of developing these cancers increases with the amount chewed or smoked and the duration of the habit.

Tobacco use includes cigarettes, cigars, pipes and smokeless tobacco (chewing or snuff). Tobacco smoke from cigarettes, cigars and pipe smoking can cause cancers in the mouth or throat, as well as other organs in the body. In addition, pipe smoking can cause a higher number of lip cancers due to the pipestem contact with the lips.

Smokeless or chewing tobacco is particularly harmful to the mouth and is associated with cancers of the cheek, gums and inner surface of the lips. Smokeless tobacco increases the risk of these cancers by 50 times as the harmful components have direct contact with the linings of the mouth. The cancer associated with smokeless tobacco often starts as leukoplakia or erythroplakia, which appear as abnormal white or red patches in the mouth

Secondhand smoke, also known as environmental tobacco smoke (ETS), may contribute to the development of oral cancers. When nonsmokers are exposed to secondhand smoke, they can absorb nicotine and other chemicals similar to the smokers. The greater the exposure to secondhand smoke, the higher the level of compounds in the body.  There are no specific statistics about the risk of oral cancers due to secondhand smoke exposure.

Alcohol use is the second strongest link to oral and throat cancers.  Scientists are unsure if alcohol directly damages the DNA, but research has shown that alcohol increases the penetration of many DNA–damaging chemicals into the cells. This is one reason why tobacco and alcohol use together cause such a large amount of DNA damage.

The ACS estimates that 75 to 80 percent of all patients with oral and oropharyngeal cancer drink excessive amounts of alcohol. These cancers are about 6 times more common in drinkers than nondrinkers.

When alcohol and tobacco use are combined, the risks of developing oral cancer varies according to the:

  • Amount and type of tobacco use
  • Length of time of smoking or smokeless tobacco
  • Amount of alcohol consumption
  • Duration of alcohol use
  • Combination of smoking and drinking

There are other risk factors for lip and mouth cancers, including:

  • Sun exposure. Prolonged exposure to the sun increases the risk of lip cancers, especially on the lower lip. The ACS estimates that more than 30 percent of people with cancers of the lip have occupations associated with significant outdoor exposure.

  • Mouth irritation. Poorly fitting dentures that cause long–term irritation of the lining is thought to be a risk factor for oral cancer. Poorly fitting dentures may allow causative cancer agents, such as alcohol and tobacco particles, to be trapped under them. Research studies, however, have not shown an increase in oral cancers between denture wearers and non-denture wearers. In addition, some studies have found individuals, particularly men, with chronic gum may have a higher risk of tongue cancer.

  • Poor nutrition. A diet low in fruits and vegetables may increase the risk of developing cancer in the oral cavity and oropharynx. Without fruits and vegetables, the cells are deprived of the nutrients that help keep them healthy.

  • Human papillomavirus (HPV) infection. Papillomaviruses are a large group of related viruses, some of which have a role in causing cancer. One type of HPV is thought to be linked to oral cancers in about 20 percent of the people. People with HPV are less likely to be smokers and drinkers and have a better prognosis for recovery from oral cancer, according to the ACS.

  • Immune system suppression. For reasons that are not clear, individuals who are taking immunosuppressive drugs are more at risk for oral and oropharyngeal cancers. These drugs are taken to treat immune system diseases or to prevent the rejection of a transplanted organ.

  • Industrial exposures. Inhalation of industrial elements, such as wood and nickel dust, may contribute to the development oral cancers. Although exposure is mostly linked to cancer of the nose and throat, some oral cancers may result from these elements.

  • Radiation. Radiation to the head and neck can increase the risk of oral and throat cancer, particularly for the salivary glands. The radiation exposure can come from diagnostic x-rays or radiation therapy for medical conditions.

Signs and symptoms of oral cancers

Signs and symptoms of mouth and lip cancers vary depending on the location of the cancer. The onset and severity of the symptoms also vary with the cancer site. For the majority of individuals, the symptoms gradually appear over time as the cancer cells grow at the site of origin. Lip cancers may be detected earlier than oral cancers because of the visibility.

Many oral cancers are not detected until the symptoms become more advanced. In some cases, a dentist may notice a problem during a regular dental examination. When detected early, squamous cell cancers can usually be successfully treated. Some conditions may indicate a cancerous or precancerous condition, such as:

  • Leukoplakia. White area in the mouth or throat. It may be the result of a noncancerous condition that will not develop into cancer, or it may be a precancerous condition (dysplasia).

  • Erythroplakia. Raised red area in mouth or throat that may bleed easily if scraped.

  • Dysplasia. A precancerous condition in the mouth or throat that may be preceded by either leukoplakia or erythroplakia. Characteristics of this condition include a white or red area. It is most often caused by tobacco use, but may be caused by mouth irritants such as poor-fitting dentures.

The most common signs and symptoms of oral cancer include:

  • Sore in the mouth or on the lips that does not heal or bleeds easily

  • Pain in the mouth that does not go away

  • Lump or thickening in the cheek or on the lip

  • Red or white patch on the gums, tongue or lining of the mouth

  • Persistent bad breath

Symptoms that may appear later include:

  • Difficulties chewing and swallowing
  • Problems moving the tongue or jaw
  • Loosening of the teeth or pain around teeth and jaw
  • Numbness around tongue or other areas of the mouth
  • Weight loss

Many of these signs or symptoms can be caused by cancer or by less serious problems. If any of these symptoms last more than two weeks, it is important to consult a physician.

Diagnosis methods for oral cancers

Some signs of oral cancers may first be noticed by a dentist during a routine examination. Dentists will refer the patient to a physician for further medical investigation. First, a physician will obtain a complete medical history, including any family history of cancer, symptoms, risk factors and other related medical information.

Following the history, the physician will conduct a complete physical examination with emphasis on the suspected areas. Because the risk of secondary cancers in the head and neck region is high for individuals with oral cancer, the physician will closely examine the pharynx, larynx, nose region and lymph nodes in the neck.

Tests that may be used to diagnose lip and oral cancer include:

  • Exfoliative cytology. The physician scrapes the suspicious lesion and places the sample on a slide. The cells are stained with a dye and examined under a microscope for abnormalities. If any of the cells are abnormal, a biopsy can be performed. The advantage of cytology is that it is performed easily with a few cells from the lesion instead of a complete tissue sample taken in a more invasive biopsy. It allows for an earlier diagnosis of cancer improving the chances for successful treatment. This test, however, does not detect all cancers and sometimes it is not possible to distinguish between cancerous and noncancerous cells (dysplasia).

  • Incisional biopsy. This procedure may be done in a physician’s office or in a medical facility, depending on the location of the tumor. It may be completed under local anesthesia with numbing of the area or under general anesthesia if the tumor is very deep.  The removed tissue is examined under a microscope by a pathologist. A biopsy can determine the type and stage of the cancer and is the only definitive way to diagnose cancer.

People with mouth and lip cancers have a higher risk for developing additional cancers in other parts of the head and neck region. Additional tests may be necessary to determine if the cancer has spread to other areas, including:

  • Endoscopy. A thin lighted tube called an endoscope is used to examine areas inside the body. Examples of tests include laryngoscopy (to view the larynx or voice box), esophagoscopy (to view the tube leading to the stomach) or bronchoscopy (to view the passages to the lungs).

  • Blood tests. Used to gain information about the general physical condition of an individual, not to diagnose oral cancers. Blood tests may show malnutrition, low red blood cell count (anemia), liver or kidney disease. They also may indicate metastasis of oral cancer to the liver or bone, prompting the need for more in-depth testing.

  • X-rays. Images taken of the head and neck on film that allow a physician to view abnormalities such as growths and tumors.

  • CAT scan.  A series of images created by a scanner and computer. These pictures allow a physician to view cross-sectional images of the region of concern. The test may be done with or without dye contrast material. CAT scans can help determine the size, shape and position of a tumor as well as enlarged lymph nodes.
  • Magnetic resonance imaging (MRI). A machine that uses a powerful magnet, radio waves and a computer to create detailed images. These pictures can allow a physician to view the head and neck in three-dimensional images to locate any abnormalities.

  • PET scan. A special radioactive sugar substance is injected into a patient’s vein and the body is viewed by a scanner. Cancer cells absorb the substance and the cancer area appears as “hot spots.” This test may be used to determine if and where cancer has spread in the body.

  • Barium swallow. This test is a series of x-rays taken after the patient has swallowed a liquid containing the chemical barium. The test allows the physician to view the structures and functioning of the mouth, throat and esophagus. A modified version of this test can be used to diagnose any swallowing difficulties

If the individual is diagnosed with cancer, the physician will need to determine the stage of the cancer. Cancer staging provides information about the extent of the disease and helps with planning treatment. It also helps predict the patient’s prognosis (outlook for survival).

Treatment options for oral cancers

Although treatment differs for the specific type of mouth and lip cancers, a team approach is best for all cancers. A group of healthcare professionals called a cancer care team can plan the best course of treatment suited for the patient. Some of the specialists that treat mouth and lip cancer patients include:

  • Dentist
  • Otolaryngologist
  • Oral surgeon
  • Medical oncologist
  • Radiation oncologist
  • Prosthodontist
  • Plastic surgeon
  • Speech language pathologist Dietitian

Treatment for mouth and lip cancers varies depending on a number of factors, including the location and stage of the cancer, as well as the patient’s general health. The patient’s age, family and peer support and the ability to tolerate treatment also affect the plan.

The treatment options for individuals with mouth or lip cancer include surgery, radiation therapy and chemotherapy. These treatment methods can be used alone or in combination, depending on a number of factors:

  • Surgery. The type and extent of surgery will depend on the size and location of the tumor. A surgeon may remove the cancer and some of the surrounding healthy tissue to obtain a “clean margin.” This helps reduce the risk of any cancer cells remaining in the tissue. In some cases, the surgeon may have to remove bone tissue from the jaw or roof of the mouth. Lymph nodes in the neck also may be removed (lymph node resection) if the physician suspects the cancer has spread beyond the area.

    Some of the surgeries used to treat oral cancers include:

    • Primary tumor resection. Removal of the tumor and surrounding tissue.

    • Full or partial mandible resection. Removal of part or all of the jaw bone in addition to the tumor.

    • Maxillectomy. Removal of part or the entire roof of the mouth (hard palate).

    • Mohs’ micrographic surgery. Used to progressively remove lip cancer in thin slices. This type of surgery reduces the amount of normal tissue removed with the cancerous tissue.

    • Dental extraction and implants. Removal of teeth if necessary for radiation therapy.

    The type of surgery can result in changes in the person’s appearance and function. Some of the changes may be permanent and some may be temporary. Complications resulting from oral surgery may include:

    • Changed appearance of face and neck (e.g., temporary swelling, permanent facial structure changes)
    • Difficulty chewing and swallowing
    • Numbness in face, throat or neck
    • Speech difficulties

  • Radiation therapy. This treatment uses high–powered x-rays to destroy cancer cells. Radiation may be provided from machines outside of the body (external radiation therapy) or from radioactive materials placed directly into or near the cancer cells (internal radiation therapy). Radiation may be used alone, with chemotherapy or with surgery. It can be effective in killing cancer cells but may also cause complications, including:
    • Redness, irritation and sores in the mouth
    • Dry mouth or thickened saliva
    • Difficulty in chewing or swallowing
    • Change or loss of taste with decreased appetite
    • Earaches from hardened ear wax
    • Swelling or drooping of skin
    • Hardening muscles and skin tissue
    • Stiffness with jaw movements

  • Chemotherapy. These powerful anti-cancer drugs are used to kill cancer cells throughout the body and may be taken orally or through the veins (intravenously). The type of drugs and schedule of treatment depend on the type and location of the cancer. Chemotherapy may be used in combination with radiation therapy and/or surgery.

    The side effects of chemotherapy are related to the type of drug and the schedule of treatment. Some of the common side effects from chemotherapy for oral cancers can include:

    • Loss of appetite
    • Nausea, vomiting and diarrhea
    • Sores in the mouth and lips
    • Hair loss
    • Tiredness and listlessness

  • Biological therapy. Some monoclonal antibodies may be used as targeted therapy for advanced cases of oral cancer. These medications can block growth factors, including one called epidermal growth factors (EGF), which has been linked to the growth of oral cancers.

Treatment also may include reconstructive surgery and rehabilitation for oral cancer surgeries. The goal of reconstructive surgery is to improve the patient’s appearance and ability to function, particularly with chewing, swallowing and speaking.

Depending on the extent of cancer surgery, surgical reconstruction may include:

  • Skin, tissue or bone grafts from other parts of the body to rebuild the jaw, mouth or throat.

  • Implant of a dental prosthesis to replace a part of the jaw.

  • Gastrostomy (hole in the abdomen) in order to receive nutrition directly into the stomach through a feeding tube if the patient is unable to eat. The tube can be removed at a later date if the patient’s condition improves.

Rehabilitation services can help a patient adjust to changes from the cancer surgery. The following professionals can help the cancer patient with specific problems:

  • Dietitian. Provides information for nutritional issues.

  • Speech pathologist. Provides therapy for swallowing problems (dysphagia) and speech difficulties. If the patient has had surgery for any removal of the tongue (glossectomy) or roof of the mouth (maxillectomy), it is likely to result in chewing and speech problems. A speech pathologist can help the patient with communication and swallowing problems.

The cure rate for mouth and lip cancers depends on the specific site and stage of the cancer. Most patients with early cancers of the lip that are treated by surgery and/or radiation have a cure rate of 90 percent or higher. Small cancers of the mouth that are detected and treated early have a similar cure rate. Moderately advanced lesions in the mouth without evidence of spreading to the lymph nodes are still generally curable with a survival rate ranging from 65 to 80 percent, according to the American Cancer Society.

Prevention methods for oral cancers

In general, eliminating or reducing the risk factors is the best way to prevent the development of oral cancer. Tobacco and alcohol are the highest risk factors for these cancers. An individual can greatly reduce the risk by not smoking and limiting alcohol intake.

In addition, people who have been diagnosed and treated for oral cancers have an increased risk for developing another cancer in the surrounding areas. The most common sites for the second cancer are in the head and neck, esophagus or lungs. For people who smoke and drink, the risk is even higher. Studies by the National Institutes of Health (NIH) have shown that individuals who continue to smoke and/or drink increase their chances of developing a second cancer for up to 20 years after the original cancer.

Other steps that can be taken to help prevent oral cancer include:

  • Well-fitting dentures and good oral hygiene. If dentures are worn, they should fit properly. Gaps can allow particles of food and tobacco to be trapped against the gums. Dentures should be cleaned and rinsed regularly. If dentures are not worn, care should be taken to maintain clean teeth and healthy gums.

  • Limit sun exposure. Ultraviolet light damages the tissues of the lips and increases the risk of oral cancer. Care should be taken to wear sunscreen and protect the face and lips from prolonged sun exposure.

  • Periodic checkups of tongue and mouth. Individuals, especially those who smoke and drink alcohol, should regularly check the tissues of their tongue and mouth. They should look for changes in color, bumps, tender spots or lumps. If any changes are noted, they should notify a dentist or physician immediately. Mouth and lip cancers can be successfully treated, but success depends on early detection. In addition, regularly scheduled dental examinations should include inspection and palpation (feeling with the fingers) of the mouth, throat and tongue by the dentist.

  • Healthy diet. Poor nutrition has been linked to oral cancer. A nutritious diet high in fruits and vegetables can supply valuable antioxidants.  Also, oral cancer patients who have chewing and swallowing problems must carefully monitor their nutritional status and use nutritional supplements when necessary.

Individuals who have had some form of oral cancer must closely monitor themselves for any changes in their general health. They should contact their physicians if they develop any signs and symptoms that might indicate the cancer has developed in another areas or returned to the original site. To help prevent a recurrence of cancer, regular examinations by healthcare professionals are recommended.

Questions for your doctor about oral cancers

Preparing questions in advance can help patients have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following questions about oral cancers:

  1. What symptoms might indicate a suspicious area in my mouth?

  2. What type of tests will be done to determine if it is cancer?

  3. Will I need a biopsy?

  4. What type of oral cancer do I have?

  5. What are my treatment options?

  6. What are the risks associated with this treatment?

  7. If I need surgery, how will it affect my appearance and function?

  8. What can be done if I am unable to eat?

  9. What type of specialists can help me during treatment?

  10. What stage is my cancer and what is my prognosis?
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