Thyroid Cancer Stages / Staging

Stages of Thyroid Cancer

Thyroid cancer staging describes how large a cancer is, and the degree to which the disease has spread. The staging guidelines developed by the American Joint Committee on Cancer (AJCC) are often used to stage thyroid cancers. The stages are based on three categories:

• T - Describes the primary tumor size.
• N – Indicates whether the thyroid cancer cells have spread to regional lymph nodes.
• M – Refers to whether the cancer has metastasized (spread to distant areas of the body).

Thyroid Cancer Stage Groupings

Once the individual TNM components are scored, they are combined to determine the overall stage group. The thyroid cancer stage classification is unique and different from most other tumor types because it incorporates not just the TNM information, but also the patient’s age and tumor subtype.

Papillary or follicular (differentiated) thyroid cancer in patients younger than 45 

The prognosis of a patient under the age of 45 with a differentiated (papillary or follicular) thyroid cancer is very good, and there is a very low chance of dying. The thyroid cancer staging system takes this information into account, and classifies these cancers simply into two groups based on whether or not they have spread to distant organs:

• Stage I: The primary tumor can be any size and the cancer may or may not have spread to lymph nodes. Distant sites in the body are not affected.
• Stage II: The primary tumor can be any size and the cancer may or may not have spread to lymph nodes, but cancer cells have spread to distant areas of the body.

Papillary or follicular (differentiated) thyroid cancer in patients 45 years of age or older AND medullary thyroid cancer (any age)

The thyroid cancer staging classification system is very similar for older patients with differentiated tumors and for those with medullary thyroid cancer. Age is not a consideration when classifying medullary cancers.

• Stage I: In this stage of thyroid cancer, the tumor is 2 cm or smaller (less than an inch wide), and has not grown outside the thyroid. It has not spread to nearby lymph nodes or distant sites.
• Stage II: Cancers at this stage meet one of the following criteria:
  • The diameter of the primary tumor ranges from 2 to 4 cm. There are no cancer cells in regional lymph nodes or distant sites in the body.
  • The primary tumor is larger than four cm in diameter or has started to grow outside of the thyroid gland. No cancer was found in the lymph nodes or other parts of the body (medullary thyroid cancer only).
• Stage III: Cancers at this stage meet one of the following criteria:
  • The primary tumor is larger than 4 cm, or has grown outside the thyroid, but has not spread to nearby lymph nodes or beyond (differentiated cancers only).
  • The tumor can be any size or be growing outside the thyroid, and has spread to lymph nodes in the neck but no farther.
• Stage IV: The most advanced stage of thyroid cancer is further subdivided depending on where the cancer has spread:
• Stage IVA: Cancers at this stage have grown beyond the thyroid gland and may have spread into nearby tissue, or they may have spread to lymph nodes in the neck and upper chest, but not to distant sites.
• Stage IVB: The primary tumor has grown into the spine or into nearby large blood vessels. In this thyroid cancer stage, the disease may or may not have spread to lymph nodes, but has not reached distant sites.
• Stage IVC: The thyroid cancer cells have metastasized, or spread to distant sites.

Anaplastic (undifferentiated) thyroid cancer 

Anaplastic/undifferentiated thyroid cancers are much more aggressive than the other subtypes and are all considered stage IV:

• Stage IVA – The primary tumor is contained within the thyroid gland, although it may or may not have spread to nearby lymph nodes. It has not spread to distant organs.
• Stage IVB - The tumor has spread outside of the thyroid gland, and cancer cells may or may not have been found in regional lymph nodes, but have not reached distant sites.
• Stage IVC - The cancer cells have spread beyond the thyroid gland to more distant parts of the body.

Thyroid Cancer Staging and Treatment Options

There are a number of different treatment options for each stage of thyroid cancer. Your medical history and other relevant factors will be carefully reviewed by your care team at CTCA to develop a personalized treatment plan for you.

Next Topic: Thyroid Cancer Treatment