What Are Oral Cavity and Oropharyngeal Cancers?
Cancer starts when cells in the body start to grow out of control. Cells in nearly any part of the body can become cancer, and can spread to other parts of the body. To learn more about how cancers start and spread, see What Is Cancer?

Oral cavity cancer, or just oral cancer, is cancer that starts in the mouth (also called the oral cavity). Oropharyngeal cancer starts in the oropharynx. This is the part of the throat just behind the mouth. Most cancers that form here are a type of cancer called squamous cell carcinoma. But other types of cancer, and other benign growths and tumors, can also form.

The oral cavity (mouth) and oropharynx (throat)
To understand these cancers, it helps to know the parts of the mouth and throat.

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, and the bony roof of the mouth (hard palate). The area behind the wisdom teeth (called the retromolar trigone) can be included as a part of the oral cavity, but it's often thought of as part of the oropharynx.

The oropharynx is the part of the throat just behind the mouth. It starts 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 walls of the throat.


illustration showing location of the back wall of the oropharynx, floor of the mouth, lower lip, gums, tonsil, retromolar trigone, soft palate, hard palate
The oral cavity and oropharynx help you breathe, talk, eat, chew, and swallow. Minor salivary glands throughout the oral cavity and oropharynx make saliva that keeps your mouth and throat moist and helps you digest food.

Tumors and growths in the oral cavity and oropharynx
Many types of tumors (abnormal growths of cells) can develop in the oral cavity and oropharynx. They fit into 3 general categories:

Benign growths are not cancer. They do not invade other tissues and do not spread to other parts of the body.
Pre-cancerous conditions are harmless growths that can turn into cancer over time.
Cancer tumors are growths that can grow into nearby tissues and spread to other parts of the body.
Benign (not cancer) tumors
Many types of benign tumors and tumor-like changes can start in the mouth or throat, such as these:

Eosinophilic granuloma
Fibroma
Granular cell tumor
Keratoacanthoma
Leiomyoma
Osteochondroma
Lipoma
Schwannoma
Neurofibroma
Papilloma
Condyloma acuminatum
Verruciform xanthoma
Pyogenic granuloma
Rhabdomyoma
Odontogenic tumors (tumors that start in tooth-forming tissues)
These non-cancerous tumors start from different kinds of cells and have a variety of causes. Some of them may cause problems, but they're not likely to be life-threatening. The usual treatment for these types of tumors is surgery to remove them completely since they are unlikely to recur (come back).

Leukoplakia and erythroplakia (possible pre-cancerous conditions)
Leukoplakia and erythroplakia are terms used to describe certain types of tissue changes that can be seen in the mouth or throat:

Leukoplakia is a white or gray patch.
Erythroplakia is a flat or slightly raised, red area that often bleeds easily if it's scraped.
Erythroleukoplakia is a patch with both red and white areas.
Your dentist or dental hygienist may be the first person to find these white or red patches. They may be cancer, they may be a pre-cancerous condition called dysplasia, or they could be a relatively harmless change.

Dysplasia is graded as mild, moderate, or severe, based on how abnormal the tissue looks under the microscope. Knowing the degree of dysplasia helps predict how likely it is to progress to cancer or go away on its own or after treatment. For example, severe dysplasia is more likely to become a cancer, while mild dysplasia is more likely to go away completely.

The most common causes of leukoplakia and erythroplakia are smoking and chewing tobacco. Poorly fitting dentures that rub against the tongue or the inside of the cheeks can also cause these changes. But sometimes, there's no clear cause. Dysplasia will often go away if the cause is removed.

A biopsy is the only way to know for certain if an area of leukoplakia or erythroplakia contains dysplastic (pre-cancerous) cells or cancer cells. (See Tests for Oral Cavity and Oropharyngeal Cancers.) But other tests may be used first to help determine if they might be cancers (and will need a biopsy) or to choose the best area to sample for a biopsy. These tests are described in Can Oral Cavity and Oropharyngeal Cancers Be Found Early?

Most cases of leukoplakia do not turn into cancer. But some leukoplakias are either cancer when first found or have pre-cancerous changes that can progress to cancer if not properly treated.