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Staging Oral Cavity Cancer

After an oral cancer diagnosis, the next step will be to determine the stage (extent). The staging system most often used for oral cavity cancer is the American Joint Committee on Cancer (AJCC) TNM system, which is based on 3 key pieces of information:

  • Tumor (T): the size and primary location of the tumor
  • Node (N): if the cancer has spread to the lymph nodes
  • Metastasis (M): whether the cancer has metastasized (spread) to other areas of the body

Your cancer can be stage 0, 1, 2, 3, or 4. The lower the number, the less the cancer has spread. A higher number, like stage 4, means a more serious cancer that has spread from where it started to other parts of the body.

T Categories for Staging Oral Cancer

"T" plus a letter or number (0 to 4) is used to describe the size and location of the tumor. Tumor size is measured in millimeters (mm) and centimeters (cm). Stage may also be divided into smaller groups that help describe the tumor in even more detail. The specific tumor stage information is as follows:

  • TX: The primary tumor cannot be evaluated.
  • Tis: A very early cancer, called carcinoma in situ, where cancer cells are found only in 1 layer of tissue.
  • T1: The tumor is 2 cm or less. It has invaded nearby tissues to a depth of 5 mm or less (called depth of invasion).
  • T2: The tumor is 2 cm or smaller, and the depth of invasion is between 5 and 10 mm. Or, the tumor is larger than 2 cm but not larger than 4 cm, and the depth of invasion is 10 mm or less.
  • T3: The tumor is greater than 4 cm, or it is any tumor with a depth of invasion greater than 10 mm.
  • T4: Tumor is considered a moderately advanced or very advanced local disease.
    • T4a: The tumor has invaded nearby structures in the mouth, such as the jaw, sinuses, or skin of the face.
    • T4b: The tumor has invaded the muscles and bones that form the mouth or the base of the skull, and/or it encases the internal arteries.

N Categories for Staging Oral Cancer

There are 2 methods of categorizing N in the TNM system: clinical and pathological. Clinical N is used for patients who have not received a neck dissection. Pathological N is used for those who have had a lymph node dissection. When cancer has spread through a lymph node and into the tissues directly surrounding it, it is called extranodal extension (ENE).

Clinical

  • NX: The regional lymph nodes cannot be evaluated.
  • N0: 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. There is no ENE.
  • N2a: The cancer has spread to a single lymph node on the same side as the primary tumor and is greater than 3 cm but less than 6 cm. No ENE is present.
  • N2b: The cancer has spread to more than 1 lymph node on the same side as the primary tumor, and none measures larger than 6 cm. No ENE is present.
  • N2c: Cancer has spread to more than 1 lymph node on either side of the body, and none measure greater than 6 cm. No ENE is present.
  • N3a: Cancer is found in a lymph node and measures greater than 6 cm. No ENE is present.
  • N3b: ENE is present in any lymph node.

Pathological

  • NX: Regional lymph nodes cannot be evaluated.
  • N0: There is no evidence of cancer in the regional lymph nodes.
  • N1: Cancer has spread to a single lymph node on the same side as the primary tumor, and the cancer found in the node measures 3 cm or less. No ENE is present.
  • N2a: Cancer has spread to 1 lymph node and is 3 cm or smaller, but no ENE is present. Or, cancer has spread to a single lymph node on the same side as the primary tumor and is greater than 3 cm but no larger than 6 cm, and no ENE is present.
  • N2b: Cancer has spread to more than 1 lymph node on the same side as the primary tumor, and none measures greater than 6 cm. No ENE is present.
  • N2c: Cancer has spread to more than 1 lymph node on either side of the body, and none measure greater than 6 cm. No ENE is present.
  • N3a: Cancer is found in a lymph node and is greater than 6 cm. No ENE is present.
  • N3b: ENE is present in a single lymph node on the same side as the primary tumor, and it is greater than 3 cm. Or, cancer has spread to many lymph nodes, and at least 1 has ENE. Or, ENE is present in a single lymph node on the opposite side of the primary tumor that is 3 cm or less.

M Categories for Staging Oral Cancer

  • M0: The cancer has not spread to other parts of the body.
  • M1: The cancer has spread to other parts of the body.

Oral Cancer Stage Grouping

The T, N, and M information is combined to determine what stage the cancer is.

Stage I: Tumor is 2 cm or smaller, and the depth of invasion is 5 mm or less. It has not spread to lymph nodes or other parts of the body (T1, N0, M0).

Stage II: Tumor is 2 cm or smaller, and the depth of invasion is between 5 and 10 mm. Or, the tumor is greater than 2 cm but not greater than 4 cm, and the depth of invasion is 10 mm or less. It has not spread to lymph nodes or other parts of the body (T2, N0, M0).

Stage III: One of the following applies:

  • Tumor is greater than 4 cm, or it is any tumor with a depth of invasion greater than 10 mm. It has not spread to lymph nodes or other parts of the body (T3, N0, M0).
  • Tumor is any size, but it has not invaded nearby structures of the oral cavity. There is cancer in a single lymph node on the same side as the primary tumor, and the cancer is 3 cm or less. No ENE is present. Cancer has not spread to other parts of the body (T1 to T3, N1, M0).

Stage IVA: One of the following applies:

  • Tumor has invaded nearby structures in the mouth, such as the jaw, sinuses, or skin of the face. If cancer has spread to a lymph node, it is to only 1 node on the same side as the primary tumor, and the cancer is 3 cm or less, with no ENE. Cancer has not spread to other parts of the body (T4a, N0 or N1, M0).
  • Tumor is small or it may have invaded nearby structures. Cancer has spread to 1 or more lymph nodes, but none is greater than 6 cm. There is no ENE. Cancer has not spread to other parts of the body (T1 to T4a, N2, M0).

Stage IVB: One of the following applies:

  • Tumor is any size. The cancer is found in a lymph node and is greater than 6 cm, but there no ENE is present; or ENE is present in any lymph node. Cancer has not spread to other parts of the body (any T, N3, M0).
  • Tumor has invaded the muscles and bones that form the mouth or the base of the skull, and/or it encases the internal arteries. The cancer may involve the lymph nodes, but it has not spread to other parts of the body (T4b, any N, M0).

Stage IVC: Cancer has spread to other parts of the body (any T, any N, M1).