Oral cancer is part of a group of cancers called head and neck cancers. Oral cancer can develop in any part of the oral cavity or oropharynx. Most oral cancers begin in the tongue and in the floor of the mouth. Almost all oral cancers begin in the flat cells (squamous cells) that cover the surfaces of the mouth, tongue, and lips. These cancers are called squamous cell carcinomas.

When oral cancer spreads (metastasizes), it usually travels through the lymphatic system. Cancer cells that enter the lymphatic system are carried along by lymph, a clear, watery fluid. The cancer cells often appear first in nearby lymph nodes in the neck.

Cancer cells can also spread to other parts of the neck, the lungs, and other parts of the body. When this happens, the new tumor has the same kind of abnormal cells as the primary tumor. For example, if oral cancer spreads to the lungs, the cancer cells in the lungs are actually oral cancer cells. The disease is metastatic oral cancer, not lung cancer. It is treated as oral cancer, not lung cancer. Doctors sometimes call the new tumor "distant" or metastatic disease.

The following are risk factors for oral cancer

• Tobacco: Tobacco use accounts for most oral cancers. Smoking cigarettes, cigars, or pipes; using chewing tobacco; and dipping snuff are all linked to oral cancer. The use of other tobacco products (such as bidis and kreteks) may also increase the risk of oral cancer. Heavy smokers who use tobacco for a long time are most at risk. The risk is even higher for tobacco users who drink alcohol heavily. In fact, three out of four oral cancers occur in people who use alcohol, tobacco, or both alcohol and tobacco.
   
• Alcohol: People who drink alcohol are more likely to develop oral cancer than people who don't drink. The risk increases with the amount of alcohol that a person consumes. The risk increases even more if the person both drinks alcohol and uses tobacco.
   
• Sun: Cancer of the lip can be caused by exposure to the sun. Using a lotion or lip balm that has a sunscreen can reduce the risk. Wearing a hat with a brim can also block the sun's harmful rays. The risk of cancer of the lip increases if the person also smokes.
   
• A personal history of head and neck cancer: People who have had head and neck cancer are at increased risk of developing another primary head and neck cancer. Smoking increases this risk.

Your regular checkup is a good time for your dentist or doctor to check your entire mouth for signs of cancer. Regular checkups can detect the early stages of oral cancer or conditions that may lead to oral cancer. Ask your doctor or dentist about checking the tissues in your mouth as part of your routine exam.

Common symptoms of oral cancer include:

• Patches inside your mouth or on your lips that are white, a mixture of red and white, or red
  
  • White patches are the most common. White patches sometimes become malignant.
     
  • Mixed red and white patches are more likely than white patches to become malignant.
     
  • Red patches are brightly colored, smooth areas that often become malignant.
     
• A sore on your lip or in your mouth that won't heal
   
• Bleeding in your mouth
   
• Loose teeth
   
• Difficulty or pain when swallowing
   
• Difficulty wearing dentures
   
• A lump in your neck
   
• An earache

Anyone with these symptoms should see a doctor or dentist so that any problem can be diagnosed and treated as early as possible. Most often, these symptoms do not mean cancer. An infection or another problem can cause the same symptoms.

If the biopsy shows that cancer is present, your doctor needs to know the stage (extent) of your disease to plan the best treatment. The stage is based on the size of the tumor, whether the cancer has spread and, if so, to what parts of the body.

The doctor may order one or more imaging tests to learn whether the cancer has spread:

• Dental x-rays: An x-ray of your entire mouth can show whether cancer has spread to the jaw.
   
• Chest x-rays: Images of your chest and lungs can show whether cancer has spread to these areas.
   
• CT scan: An x-ray machine linked to a computer takes a series of detailed pictures of your body. You may receive an injection of dye. Tumors in the mouth, throat, neck, or elsewhere in the body show up on the CT scan.
   
• MRI: A powerful magnet linked to a computer is used to make detailed pictures of your body. The doctor can view these pictures on a monitor and can print them on film. An MRI can show whether oral cancer has spread.