Oral and Oropharyngeal Cancer: Stages and Grades

Approved by the Cancer.Net Editorial Board, 07/2016

ON THIS PAGE: You will learn about how doctors describe a cancer’s growth or spread. This is called the stage. To see other pages, use the menu.

Staging is a way of describing where a cancer is located, if or where it has spread, and whether it is affecting other parts of the body. Doctors use diagnostic tests to find out the cancer’s stage, so staging may not be complete until all the tests are finished. Knowing the stage helps the doctor to decide what kind of treatment is best and can help predict a patient’s prognosis, which is the chance of recovery. There are different stage descriptions for different types of cancer.

TNM staging system

One tool that doctors use to describe the stage is the TNM system. Doctors use the results from diagnostic tests and scans to answer these questions:

  • Tumor (T): How large is the primary tumor? Where is it located?

  • Node (N): Has the tumor spread to the lymph nodes? If so, where and how many?

  • Metastasis (M): Has the cancer metastasized to other parts of the body? If so, where and how much?

The results are combined to determine the stage of cancer for each person. There are 5 stages: stage 0 (zero) and stages I through IV (one through four). The stage provides a common way of describing the cancer, so doctors can work together to plan the best treatments.

Here are more details on each part of the TNM system for oral and oropharyngeal cancer.

Tumor (T)

Using the TNM system, the "T" plus a letter or number (0 to 4) is used to describe the size and location of the tumor. Some stages are also divided into smaller groups that help describe the tumor in even more detail. Specific tumor stage information is listed below.

TX: The primary tumor cannot be evaluated.

T0 (T plus zero): No evidence of a tumor is found.

Tis: Describes a stage called carcinoma (cancer) in situ. This is a very early cancer where cancer cells are found only in 1 layer of tissue.

T1: The tumor is 2 centimeters (cm) at its greatest dimension.

T2: The tumor is larger than 2 cm but not larger than 4 cm.

T3: The tumor is larger than 4 cm.

T4a (lip): The tumor began on the lip but has invaded adjacent tissue, such as the bone floor of the mouth or the skin of the face.

T4a (oral cavity): The tumor has invaded through the cortical bone deep into structures in the mouth, such as the muscle of the tongue or into the sinuses.

T4a (oropharynx): The tumor has spread to the larynx, tongue, or jawbone.

T4b (oral cavity): The tumor has invaded the base of the skull and/or encases the internal arteries.

T4b (oropharynx): The tumor has spread into the nasopharynx, skull base, or nearby arteries and muscles.

Node (N)

The “N” in the TNM staging system stands for lymph nodes. These tiny, bean-shaped organs help fight infection. Lymph nodes near where the cancer started are called regional lymph nodes. Lymph nodes in other parts of the body are called distant lymph nodes. There are many lymph nodes in the head and neck area. Careful assessment of lymph nodes is an important part of staging.

NX: The regional lymph nodes cannot be evaluated.

N0 (N plus zero): There is no evidence of cancer in the regional lymph nodes.

N1: The cancer has spread to a single lymph node on the same side as the primary tumor, and the cancer found in the node is 3 cm or smaller.

N2a: Cancer has spread to a single lymph node on the same side as the primary tumor and is larger than 3 cm but not larger than 6 cm.

N2b: Cancer has spread to more than 1 lymph node on the same side as the primary tumor, and none measure larger than 6 cm.

N2c: Cancer has spread to more than 1 lymph node on either side of the body, and none measure larger than 6 cm.

N3: The cancer found in the lymph nodes and is larger than 6 cm.

Metastasis (M)

The "M" in the TNM system indicates whether the cancer has spread to other parts of the body, called distant metastasis.

MX: Distant metastasis cannot be evaluated.

M0 (M plus zero): Cancer has not spread to other parts of the body.

M1: Cancer has spread to other parts of the body.

Cancer stage grouping

Doctors combine the T, N, and M information to say what stage the cancer is.

Stage 0: Describes a carcinoma in situ (Tis) with no spread to lymph nodes (N0) or distant metastasis (M0).

Stage I: Describes a small tumor (T1) with no spread to lymph nodes (N0) and no distant metastasis (M0).

Stage II: Describes a tumor that is smaller than 4 cm (T2) and has not spread to lymph nodes (N0) or to distant parts of the body (M0).

Stage III: Describes a larger tumor (T3) with no spread to lymph nodes (N0) or metastasis (M0), as well as smaller tumors (T1, T2) that have spread to regional lymph nodes (N1) but have no sign of metastasis (M0).

Stage IVA: Describes any invasive tumor (T4a) with either no lymph node involvement (N0) or spread to only a single, same-sided lymph node (N1) but no metastasis (M0). It is also used for any tumor (any T) with more significant nodal involvement (N2) but no metastasis (M0).

Stage IVB: Describes any tumor (any T) with extensive nodal involvement (N3) but no metastasis (M0).

Stage IVC: Indicates there is evidence of distant spread (any T, any N, M1).

Recurrent: Recurrent cancer is cancer that has come back after treatment. If the cancer does return, there will be another round of tests to learn about the extent of the recurrence. These tests and scans are often similar to those done at the time of the original diagnosis.

Grade (G)

Doctors also describe this type of cancer by its grade (G), which describes how much cancer cells look like healthy cells when viewed under a microscope. The doctor compares the cancerous tissue with healthy tissue. Healthy tissue usually contains many different types of cells grouped together. If the cancer looks similar to healthy tissue and contains different cell groupings, it is called differentiated or a low-grade tumor. If the cancerous tissue looks very different from healthy tissue, it is called poorly differentiated or a high-grade tumor. The cancer’s grade can help the doctor predict how quickly the cancer will spread. In general, the lower the tumor’s grade, the better the prognosis.

GX: The grade cannot be evaluated.

G1: The cells look more like normal tissue and are well differentiated.

G2: The cells are only moderately differentiated.

G3 and G4: The cells don’t resemble normal tissue and are poorly differentiated.

Used with permission of the AJCC, Chicago, Illinois. The original source for this material is the AJCC Cancer Staging Manual, Seventh Edition, published by Springer-Verlag New York, www.cancerstaging.org. Please note that AJCC’s Eighth Edition (2017) has been released; related changes to the information provided above are underway. Please check back soon for updated staging definitions or talk with your doctor about whether these changes affect your diagnosis.

Information about the cancer’s stage will help the doctor recommend a specific treatment plan. The next section in this guide is Treatment Options. Or, use the menu to choose another section to continue reading this guide.