Oral cavity and oropharyngeal cancer
Oral cancer starts in the mouth, also called the oral cavity. The oral cavity includes the lips, the inside lining of the lips and cheeks (buccal mucosa), the teeth, the gums, the front two-thirds of the tongue, the floor of the mouth below the tongue, the bony roof of the mouth (hard palate), and the area behind the wisdom teeth (retromolar trigone).

Oropharyngeal cancer develops in the part of the throat just behind the mouth, called the oropharynx. Sometimes this is called throat cancer. The oropharynx begins where the oral cavity stops. It includes the base of the tongue (the back third of the tongue), the soft palate (the back part of the roof of the mouth), the tonsils, and the side and back wall of the throat.

The oral cavity and oropharynx help you breathe, talk, eat, chew, and swallow. Minor salivary glands located throughout the oral cavity and oropharynx make saliva that keeps your mouth moist and helps you digest food.

The oral cavity and oropharynx have several types of body tissues, and each of these tissues is made up of several types of cells. Different cancers can develop from each type of cell. The differences are important, because they can influence a person's treatment options and prognosis (outlook).

Cancerous oral cavity and oropharyngeal tumors
Several types of cancers can start in the mouth or throat.

Squamous cell carcinomas
More than 90% of cancers of the oral cavity and oropharynx are squamous cell carcinomas, also called squamous cell cancers. Squamous cells are flat, scale-like cells that normally form the lining of the mouth and throat. Squamous cell cancer begins as a collection of abnormal squamous cells.

The earliest form of squamous cell cancer is called carcinoma in situ, meaning that the cancer cells are present only in the outer layer of cells called the epithelium. This is different from invasive squamous cell carcinoma, where the cancer cells have grown into deeper layers of the oral cavity or oropharynx.

Verrucous carcinoma
Verrucous carcinoma is a type of squamous cell carcinoma that makes up less than 5% of all oral cavity tumors. It is a low-grade (slow growing) cancer that rarely spreads to other parts of the body but can deeply spread into surrounding tissue. Another concern is that over time, areas of ordinary squamous cell cancer may develop within some verrucous carcinomas. And, some verrucous carcinomas may have areas of ordinary squamous cell cancer that are not recognized in the biopsy sample. Cells from these areas of squamous cell carcinoma can metastasize to other parts of the body. For all of these reasons, verrucous carcinomas should be promptly removed along with a wide margin of surrounding tissue.

Minor salivary gland carcinomas
Minor salivary gland cancers can develop in the glands that are found throughout the lining of the mouth and throat. There are several types of minor salivary gland cancers, including adenoid cystic carcinoma, mucoepidermoid carcinoma, and polymorphous low-grade adenocarcinoma. For more information about these cancers and benign salivary gland tumors, see the American Cancer Society document, Salivary Gland Cancer.

Lymphomas
The tonsils and base of the tongue contain immune system (lymphoid) tissue that can develop into a cancer called a lymphoma. For more information about these cancers refer to the American Cancer Society documents, Non-Hodgkin Lymphoma, Non-Hodgkin Lymphoma in Children, and Hodgkin Disease.

Oral cavity and oropharyngeal cancer treatment

The type of treatment your doctor will recommend depends on the tumor site and how far the cancer has spread. This section summarizes options usually considered for each stage of oral cavity or oropharyngeal cancer. These are general comments about the treatment, because the approach to each site may be different.

Stage 0 (carcinoma in situ)

Although cancer in this stage has not become invasive (started to grow into deeper layers of tissue), it can do so. The usual treatment is to remove the top layers of tissue along with a small margin of normal tissue. This is known as surgical stripping or thin resection. Close follow-up to see if any cancer has come back (recurrence) is important. Carcinoma in situ that keeps coming back after resection may require radiation therapy. About 95% to 100% of patients at this stage survive a long time without the need for significant surgery. It is important for these patients to realize that continuing to smoke increases the risk that a new cancer will develop.

Stages I and II

Most patients with stage I or II oral cavity and oropharyngeal cancer can be successfully treated with either surgery or radiation therapy. Both approaches work equally well in treating these cancers. The choice of treatment is influenced by the expected side effects.

Lip: Lip cancer is generally treated with surgery, including Mohs surgery. Radiation therapy or more extensive surgery may be used if the tumor turns out to be larger than expected. If needed, special reconstructive surgery can help correct the defect in the lip.

Radiation alone may also be used as the first treatment. This can be either external beam or brachytherapy (or sometimes a combination of the 2). Surgery may be used if radiation doesn't completely get rid of the tumor.

If the tumor is thick, the surgeon may remove and examine lymph nodes in the neck.

Floor of the mouth: Surgery is preferred if it can be done because of possible bone damage from radiation. If the cancer does not appear to have been completely removed by surgery, radiation may be added. This cancer readily spreads to neck lymph nodes. Surgery (neck dissection) may be recommended to remove these. Usually, the surgeon will remove lymph nodes from the side of the neck nearest the tumor. But if the tumor is in the middle, then lymph nodes on both sides of the neck will need to be removed.

Front of the tongue: Surgery is preferred for small tumors and radiation for larger ones, especially if cutting these out would impair speech or swallowing. If surgery could not remove all the cancer, radiation may be added. For larger tumors, surgery or radiation to treat neck lymph nodes will likely be recommended.

Buccal mucosa (cheek): These cancers are usually treated with surgery. Radiation may be recommended instead. If surgery is used, radiation may be added. If the tumor is large, the neck lymph nodes will be removed as well.

Stages III and IV
More advanced oral cavity and oropharyngeal cancers generally require a combination of either surgery and radiation, or radiation and either chemotherapy or cetuximab. The effect of combining radiation with both chemotherapy and cetuximab is also being studied. The choice of treatment is influenced by the expected side effects and the patient's current health status.

Surgery usually includes a neck dissection because of the high risk of cancer spread to the lymph nodes. Radiation therapy often is required after surgery, particularly if the tumor has spread to the lymph nodes. The amount of tissue removed depends on the extent of cancer, and the method of reconstruction depends on the surgical defect created.

Primary tumors that are too large to be completely removed by surgery are often treated with radiation, either alone or with chemotherapy. Another option may be to use cetuximab along with the radiation.

Cancers that have already spread to other parts of the body are usually treated with either a single drug or combined chemotherapy. Other treatments such as radiation may also be used to help relieve symptoms from the cancer or to help prevent problems from occurring.

Clinical trials are looking at different ways of combining radiation and chemotherapy with or without cetuximab or other new agents to improve survival and quality of life, and reduce the need for radical resection of advanced oral cavity and oropharyngeal cancers.