Oropharyngeal Throat Cancer Staging

What is oropharyngeal throat cancer staging?

After an oropharyngeal cancer diagnosis, oncologists proceed to ‘stage’ the tumor with the help of imaging scans (CT Scan), endoscopy tests, blood tests, etc. They can classify the tumor across various categories on the basis of its spread. If the tumor is confined to the primary site of origin, then it is referred to as localized (early stage) disease. If it has spread to a nearby site, or if there is any lymph node involvement, then it is termed as locally advanced, and if cancer has spread to other distant organs in the body, then it is labelled as a metastatic disease. This entire process is called staging.

Oropharyngeal cancer staging explained with an image of oropharynx anatomy

What information is provided by the staging of oropharyngeal cancer?

The stage of oropharyngeal cancer provides information on how aggressively cancer has spread within a patient’s body and is extremely helpful in determining the best course of action for a patient who has been diagnosed at a specific stage of the disease.

The stage of oropharyngeal cancer is also useful in determining the probable outcomes and projected survival rate of a particular patient.

How is oropharyngeal throat cancer staged?

Note: Oropharynx cancer staging adopts the same TNM strategy as used in the staging of cancers of the oral cavity, which also belong to the head & neck cancers family.

Oropharyngeal cancer staging is dependent on the TNM system, developed by the American Joint Committee on Cancer (AJCC). TNM staging principles are based on the following three factors:

  • T – This represents the size of the main tumor, and indicates how far the tumor has grown inside the oropharynx and in nearby tissue areas.
  • N – This represents cancer’s extent of spread into nearby lymph nodes, and determines the number and size of the affected lymph nodes.
  • M – This represents the status of metastasis (spread) to distant organs in the body (commonly: the lungs, liver or bones)

Once the T, N and M aspects of the disease have been established via the right diagnostic systems, the information is consolidated to form a group stage for the grade of oropharyngeal cancer that a specific patient exhibits. This is called the clinical stage of the disease.

Read more on what is throat cancer

What are the different stages of oropharyngeal throat cancer?

Stage 0

(Tis | N0 | M0)

In Stage 0 oropharyngeal cancer:

  • The cancer is contained within the top layer of the cellular lining of the oropharynx. The tumor has not yet grown into deeper layers (Tis).
  • Cancer has not spread to any of the nearby lymph nodes (N0).
  • Cancer has not metastasized to distant organs in the body (M0).

Stage 1

(T1 | N0 | M0)

In Stage 1 oropharyngeal cancer:

  • The tumor is less than or equal to 2 cms in size and is not growing into nearby tissue areas (T1).
  • Cancer has not spread to any of the nearby lymph nodes (N0).
  • Cancer has not metastasized to distant organs in the body (M0).

Stage 2

(T2 | N0 | M0)

In Stage 2 oropharyngeal cancer:

  • The tumor is larger than 2 cms in size and lesser than 4 cms in size. It is not growing into nearby tissue areas (T2).
  • Cancer has not spread to any of the nearby lymph nodes (N0).
  • Cancer has not metastasized to distant organs in the body (M0).

 

Stage 3

(T3 | N0 | M0) or (T1 to T3 | N1 | M0)

In Stage 3 oropharyngeal cancer:

  • The tumor is larger than 4 cms in size and may have grown into the epiglottis, or the base of the tongue (T3).
  • Cancer has not spread to any of the nearby lymph nodes (N0).
  • Cancer has not metastasized to distant organs in the body (M0).

An alternate scenario for Stage 3:

  • The tumor is of a variable size and may have grown into nearby tissue areas (T1 to T3).
  • Cancer has affected one lymph node (present on the same side of the neck as the tumor). This lymph node is less than 3 cms in size(N1).
  • Cancer has not metastasized to distant organs in the body (M0).

Stage 4 (advanced oropharyngeal cancer)

(T1 to T4c | N0 to N3 | M0 to M1)

In Stage 4 of oropharyngeal throat cancer:

  • The tumor may be of any size and may have invaded parts of the soft tissue surrounding the oropharynx. This can be classified as moderate to extremely advanced local disease (T1 to T4c).
  • It is possible that the lymph nodes have not been affected at all (N0), or a single node less than 3 cms in size may have been affected (N1). In moderately advanced local disease scenarios, a 3 to 6 cm sized lymph node on the same side as the tumor might be affected (N2), and in cases of an extremely advanced local disease, more than one lymph node, larger than 6 cms in size may become affected (N3).
  • It is possible that the extent of the disease remains local (moderately advanced or extremely advanced local disease – M0), or that oropharyngeal cancer has started spreading to other organs in the body, starting with the lungs (M1).

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