Staging is the process of finding out how far a cancer has spread. The outlook (prognosis) for people with cancer depends, to a large extent, on the cancer's stage. The stage of oral cavity and oropharyngeal cancers is one of the most important factors in choosing treatment.

Staging information is based on the results of the physical exam, endoscopy, and imaging tests (CT scan, MRI, chest x-ray, and/or PET scans), which are described in the section, "How are oral cavity and oropharyngeal cancers diagnosed?"

The TNM staging system

A staging system is a standard way for doctors to describe and summarize how far a patient's cancer has spread. The most common system used to describe the extent of oral cavity and oropharyngeal cancers is the TNM system of the American Joint Committee on Cancer (AJCC). The TNM system for staging describes 3 key pieces of information:

• T indicates the size of the main (primary) tumor and which, if any, tissues of the oral cavity or oropharynx it has spread to.

• N describes the extent of spread to nearby (regional) lymph nodes. Lymph nodes are small bean-shaped collections of immune system cells that are important in fighting infections. Cells from oral cavity or oropharyngeal cancers can travel to lymph nodes in the neck area.

• M indicates whether the cancer has spread (metastasized) to other organs of the body. (The most common site of spread is to the lungs. The next most common sites are the liver and bones.)

Numbers or letters appear after T, N, and M to provide details about each of these factors:

• The numbers 0 through 4 indicate increasing severity.
• The letter X means "cannot be assessed" because the information is not available.

T categories for cancers of the lip, oral cavity, and oropharynx:

TX: primary tumor cannot be assessed; information not known

T0: no evidence of primary tumor

Tis: carcinoma in situ. This means the cancer is still within the epithelium (the top layer of cells lining the oral cavity and oropharynx) and has not yet grown into deeper layers of oral or oropharyngeal tissue

T1: tumor is 2 cm (about ¾ inch) across or smaller

T2: tumor is larger than 2 cm across, but smaller than 4 cm (about 1 ½ inch)

T3: tumor is larger than 4 cm across

T4a: The tumor is growing into nearby structures. This is known as moderately advanced local disease.

• For oral cavity cancers: the tumor is growing into nearby structures, such as the bones of the jaw or face, deep muscle of the tongue, skin of the face, or the maxillary sinus.

• For lip cancers: the tumor is growing into nearby bone, the inferior alveolar nerve (the nerve to the jawbone), the floor of the mouth, or the skin of the chin or nose.

• For oropharyngeal cancers: the tumor is growing into the larynx (voicebox), the tongue muscle, or bones such as the medial pterygoid, the hard palate, and the jaw.

T4b: The tumor has grown through nearby structures and into deeper areas or tissues. This is known as very advanced local disease. Any of the following may be true:

• The tumor is growing into other bones, such as the pterygoid plates and/or the skull base (for any oral cavity or oropharyngeal cancer).

• The tumor surrounds the internal carotid artery (for any oral cavity or oropharyngeal cancer).

• For lip and oral cavity cancers: the tumor is growing into an area called the masticator space.

• For oropharyngeal cancers: the tumor is growing into a muscle called the lateral pterygoid muscle.

• For oropharyngeal cancers: the tumor is growing into the nasopharynx (the area of the throat that is behind the nose).

N categories:

NX: nearby lymph nodes cannot be assessed; information not known

N0: no spread to nearby lymph nodes

N1: the cancer has spread to one lymph node on the same side of the head or neck as the primary tumor; this lymph node is smaller than 3 cm (about 1 ¼ inch) across

N2 includes 3 subgroups:

N2a: the cancer has spread to one lymph node on the same side as the primary tumor; the lymph node larger than 3 cm across but smaller than 6 cm (about 2 ½ inches)

N2b: the cancer has spread to 2 or more lymph nodes on the same side as the primary tumor, but none are larger than 6 cm across

N2c: the cancer has spread to one or more lymph nodes on both sides of the neck or on the side opposite the primary tumor, but none are larger than 6 cm across

N3: the cancer has spread to a lymph node that is larger than 6 cm across

M categories:

MX: presence of distant spread cannot be assessed; information not known

M0: no distant spread

M1: the cancer has spread to distant sites outside the head and neck region (for example, the lungs)

Stage grouping

Once the T, N, and M categories have been assigned, this information is combined by a process called stage grouping to assign an overall stage of 0, I, II, III, or IV. Stage IV is further divided into A, B, and C.

Stage 0: Tis, N0, M0: Carcinoma in situ. The cancer is only growing in the epithelium, the outer layer of oral or oropharyngeal tissue (Tis). It has not yet grown into a deeper layer or spread to nearby structures, lymph nodes (N0), or distant sites (M0).

Stage I: T1, N0, M0: The tumor is 2 cm (about ¾ inch) across or smaller (T1) and has not spread to nearby structures, lymph nodes (N0), or distant sites (M0).

Stage II: T2, N0, M0: The tumor is larger than 2 cm across but smaller than 4 cm (T2) and has not spread to nearby structures, lymph nodes (N0), or distant sites (M0).

Stage III: One of the following applies:

T3, N0, M0: The tumor is larger than 4 cm across, but it hasn't grown into nearby structures or spread to the lymph nodes (N0) or distant sites (M0).

OR

T1 to T3, N1, M0: The tumor is any size and hasn't grown into nearby structures (T1 to T3). It has spread to one lymph node on the same side of the head or neck, which is smaller than 3 cm across (N1). The cancer hasn't spread to distant sites (M0).

Stage IVA: One of the following applies:

T4a, N0 or N1, M0: The tumor is growing into nearby structures (T4a). It can be any size. It has either not spread to the lymph nodes (N0) or has spread to one lymph node, on the same side of the head or neck, which is smaller than 3 cm across (N1). The cancer hasn't spread to distant sites (M0).

OR

T1 to T4a, N2, M0: The tumor is any size and may or may not invade nearby structures. It has not spread to distant sites (M0). It has spread to one of the following:

• one lymph node one the same side of the head and neck that is between 3 and 6 cm across (N2a)
• one lymph node on the opposite side of the head and neck that is less than 6 cm across (N2b)
• 2 or more lymph nodes, all of which are smaller than 6 cm across. The lymph nodes can be on any side of the neck (N2c)

Stage IVB: One of the following applies:

T4b, any N, M0: The tumor is growing into deeper areas and/or tissues (very advanced local disease - T4b). It may (or may not) have spread to lymph nodes (any N). It has not spread to distant sites (M0).

OR

Any T, N3, M0: The tumor is any size and it may or may not have grown into other structures (any T). It has spread to one or more lymph nodes larger than 6 cm across (N3), but it hasn't spread to distant sites (M0).

Stage IVC: Any T, Any N, M1: The tumor is any size, and it may or may not have spread to lymph nodes. It has spread to distant sites, most commonly the lungs.

Recurrent (relapsed) cancer

This is not an actual stage in the TNM system. Recurrent (relapsed) disease means that the cancer has come back (recurred) after treatment. Recurrent oral cavity or oropharyngeal cancer may return in the mouth or throat (local recurrence), in the lymph nodes (regional relapse) or in another part of the body (distant recurrence, usually in the lungs).

Talk with your doctor, if you have any questions about the stage of your cancer or how it affects your treatment.

Relative 5-year survival rates, by stage

Survival rates are often used by doctors as a standard way of discussing a person's prognosis (outlook). Some patients with cancer may want to know the survival statistics for people in similar situations, while others may not find the numbers helpful, or may even not want to know them. Whether or not you want to read about the survival statistics below for oral cavity and oropharyngeal cancer is up to you.

The 5-year survival rate refers to the percentage of patients who live at least 5 years after their cancer is diagnosed. Of course, many people live much longer than 5 years (and many are cured).

Five-year relative survival rates assume that some people will die of other causes and compares the observed survival of people with cancer with that expected for people without cancer. This is a more accurate way to describe the outlook for patients with a particular type and stage of cancer.

In order to get 5-year survival rates, doctors have to look at people who were treated at least 5 years ago. Improvements in treatment since then may result in a more favorable outlook for people now being diagnosed with oral cavity and oropharyngeal cancer.

Survival rates are often based on previous outcomes of large numbers of people who had the disease, but they cannot predict what will happen in any particular person's case. Many other factors may affect a person's outlook, such as underlying health problems and how well the cancer responds to treatment. Your doctor can tell you how the numbers below may apply to you, as he or she is familiar with the aspects of your particular situation.

The following survival statistics come from the National Cancer Institute's SEER program. They are based on patients treated between 1988 and 2001.

Lip

Tongue

Floor of the mouth

Gum and other mouth

Oropharynx and tonsil

* The numbers given are correct, but they indicate that for cancers of the oropharynx and tonsil, the 5-year survival for stages I, II, and III are essentially the same

Last Medical Review: 09/24/2009
Last Revised: 09/24/2009