Thyroid Cancer Staging

Thyroid Cancer Staging

Thyroid cancer staging measures the degree to which the disease has spread. This information is used by doctors to identify potential treatment options. 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 - Indicates information about the primary tumor size
• N - Explains the spread of cancer to regional lymph nodes
• M - Describes whether the cancer has metastasized (spread to distant areas of the body)

The results of physical exams and diagnostic testing are used to rate these factors. For example, the T1 tumor is smaller and less invasive than a T4 tumor. If the cancer has metastasized, it is rated M1, but if it is localized to the site of origin it is rated M0. An "X" is used as placeholder if there is not enough information about a particular factor. The three factors, T, N and M, are grouped together into stages using roman numerals I-IV.

Stage Groupings for Differentiated Thyroid Cancers & MTC

Thyroid cancer staging may depend on the type of cancer and the age of the patient. Therefore, staging for patients under and over 45 years of age is listed.

Staging for Papillary and Follicular Thyroid Cancer Patients Under 45

The following stage groupings only apply to patients with papillary or follicular thyroid carcinomas under the age of 45:

• Stage I Thyroid Cancer - 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 Thyroid Cancer - The cancer has spread to distant sites, but may or may not have spread to regional lymph nodes.

Staging for Medullary Thyroid Carcinoma (MTC) and Patients Over 45

Age is not a factor in staging patients diagnosed with medullary thyroid carcinoma (MTC). The same criteria for patients over 45 with papillary or follicular thyroid carcinomas also apply to MTC staging:

• Stage I Thyroid Cancer - The diameter of the tumor is no more than two cm (less than an inch wide). No cancer was found in regional lymph nodes or distant sites in the body.

• Stage II Thyroid Cancer - The spread and the growth of the cancer may be qualified in two ways:

  • The diameter of the primary tumor has grown and ranges from two to four cm. No cancer was found in regional lymph nodes or distant sites in the body.
  • The primary tumor is larger than four cm in diameter has started to grown outside of the thyroid. No cancer was found in the lymph nodes or other parts of the body.

• Stage III Thyroid Cancer - The spread and the growth of the cancer may be qualified in two ways:

  • The tumor can be any size and may have grown slightly outside the thyroid.
  • The tumor has spread to lymph nodes around the thyroid in the neck but not to distant sites.

• Stage IV Thyroid Cancer - The most advanced stage of thyroid cancer is differentiated in to Stage IVA, Stage IVB or Stage IVC depending on where the cancer has spread to:

  • Stage IVA - Cancers in this stage have grown beyond the thyroid gland and have spread into nearby tissue. Cancers in this stage may have also 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. The cancer may or may not have spread to lymph nodes, but has not reached distant sites.
  • Stage IVC - The thyroid cancer has spread to distant sites, but may or may not have grown outside of the thyroid or into the lymph nodes.

Undifferentiated Thyroid Cancer Stage Groupings

Anaplastic/undifferentiated thyroid cancers are more aggressive and are all considered stage IV:

• Thyroid Cancer IVA - In this case, it may be possible to surgically remove the tumor. It is possible that the cancer has spread to the lymph nodes.
• Thyroid Cancer IVB - The tumor is inoperable and has spread outside of the thyroid. In this classification, the cancer may or may not have been found in regional lymph nodes.
• Thyroid Cancer IVC - The cancer has spread elsewhere in the body. The tumor may or may not have grown outside of the thyroid or to the regional lymph nodes.

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