Stages of Thyroid Cancer

After thyroid cancer has been diagnosed, tests are done to find out if cancer cells have spread within the thyroid or to other parts of the body.

The process used to find out if cancer has spread within the thyroid or to other parts of the body is called staging. The information gathered from the staging process determines the stage of the disease. It is important to know the patient's age and the stage of the cancer to plan treatment.

The following tests and procedures may be used in the staging process:

• CT scan (CAT scan): A procedure that makes a series of detailed pictures of areas inside the body, such as the chest, abdomen, and brain, taken from different angles. The pictures are made by a computer linked to an x-ray machine. A dye may be injected into a vein or swallowed to help the organs or tissues show up more clearly. This procedure is also called computed tomography, computerized tomography, or computerized axial tomography.
• Ultrasound exam: A procedure in which high-energy sound waves (ultrasound) are bounced off internal tissues or organs and make echoes. The echoes form a picture of body tissues called a sonogram. The picture can be printed to be looked at later.
• Chest x-ray: An x-ray of the organs and bones inside the chest. An x-ray is a type of energy beam that can go through the body and onto film, making a picture of areas inside the body.
• Bone scan: A procedure to check if there are rapidly dividing cells, such as cancer cells, in the bone. A very small amount of radioactive material is injected into a vein and travels through the bloodstream. The radioactive material collects in the bones with cancer and is detected by a scanner.
• Sentinel lymph node biopsy: The removal of the sentinel lymph node during surgery. The sentinel lymph node is the first lymph node in a group of lymph nodes to receive lymphatic drainage from the primary tumor. It is the first lymph node the cancer is likely to spread to from the primary tumor. A radioactive substance and/or blue dye is injected near the tumor. The substance or dye flows through the lymph ducts to the lymph nodes. The first lymph node to receive the substance or dye is removed. A pathologist views the tissue under a microscope to look for cancer cells. If cancer cells are not found, it may not be necessary to remove more lymph nodes.

There are three ways that cancer spreads in the body.

Cancer can spread through tissue, the lymph system, and the blood:

• Tissue. The cancer spreads from where it began by growing into nearby areas.
• Lymph system. The cancer spreads from where it began by getting into the lymph system. The cancer travels through the lymph vessels to other parts of the body.
• Blood. The cancer spreads from where it began by getting into the blood. The cancer travels through the blood vessels to other parts of the body.

Cancer may spread from where it began to other parts of the body.

When cancer spreads to another part of the body, it is called metastasis. Cancer cells break away from where they began (the primary tumor) and travel through the lymph system or blood.

• Lymph system. The cancer gets into the lymph system, travels through the lymph vessels, and forms a tumor (metastatic tumor) in another part of the body.
• Blood. The cancer gets into the blood, travels through the blood vessels, and forms a tumor (metastatic tumor) in another part of the body.

The metastatic tumor is the same type of cancer as the primary tumor. For example, if thyroid cancer spreads to the lung, the cancer cells in the lung are actually thyroid cancer cells. The disease is metastatic thyroid cancer, not lung cancer.

Stages are used to describe thyroid cancer based on the type of thyroid cancer and the age of the patient:

Papillary and follicular thyroid cancer in patients younger than 55 years

• Stage I: In stage I papillary and follicular thyroid cancer, the tumor is any size and may have spread to nearby tissues and lymph nodes. Cancer has not spread to other parts of the body.
• Stage II: In stage II papillary and follicular thyroid cancer, the tumor is any size and cancer may have spread to nearby tissues and lymph nodes. Cancer has spread from the thyroid to other parts of the body, such as the lungs or bones.

Papillary and follicular thyroid cancer in patients 55 years and older

• Stage I: In stage I papillary and follicular thyroid cancer, cancer is found in the thyroid only and the tumor is 4 centimeters or smaller.
• Stage II: In stage II papillary and follicular thyroid cancer, one of the following is found:
  • cancer is found in the thyroid and the tumor is 4 centimeters or smaller; cancer has spread to nearby lymph nodes; or
  • cancer is found in the thyroid, the tumor is larger than 4 centimeters, and cancer may have spread to nearby lymph nodes; or
  • the tumor is any size and cancer has spread from the thyroid to nearby muscles in the neck and may have spread to nearby lymph nodes.
  
• Stage III: In stage III papillary and follicular thyroid cancer, the tumor is any size and cancer has spread from the thyroid to soft tissue under the skin, the esophagus, the trachea, the larynx, or the recurrent laryngeal nerve (a nerve that goes to the larynx). Cancer may have spread to lymph nodes.
• Stage IV: Stage IV papillary and follicular thyroid cancer is divided into stages IVA and IVB.
  • In stage IVA, the tumor is any size and cancer has spread to tissue in front of the spine or has surrounded the carotid artery or the blood vessels in the area between the lungs. Cancer may have spread to lymph nodes.
  • In stage IVB, the tumor is any size and cancer has spread to other parts of the body, such as the lungs or bones. Cancer may have spread to lymph nodes.

Anaplastic thyroid cancer in patients of all ages

Anaplastic thyroid cancer grows quickly and usually has spread within the neck when it is found. Anaplastic thyroid cancer is considered stage IV thyroid cancer. Stage IV anaplastic thyroid cancer is divided into stages IVA, IVB, and IVC.

• In stage IVA, cancer is found in the thyroid only and the tumor may be any size.
• In stage IVB, one of the following is found:
  • cancer is found in the thyroid and the tumor may be any size; cancer has spread to nearby lymph nodes; or
  • the tumor is any size and cancer has spread from the thyroid to nearby muscles in the neck and may have spread to nearby lymph nodes; or
  • the tumor is any size and cancer has spread from the thyroid to soft tissue under the skin, the esophagus, the trachea, the larynx, the recurrent laryngeal nerve (a nerve that goes to the larynx), or tissue in front of the spine, or has surrounded the carotid artery or the blood vessels in the area between the lungs; cancer may have spread to lymph nodes.
• In stage IVC, the tumor is any size and cancer has spread to other parts of the body, such as the lungs or bones. Cancer may have spread to lymph nodes.

Medullary thyroid cancer in patients of all ages

• Stage I: In stage I medullary thyroid cancer, cancer is found in the thyroid only and the tumor is 2 centimeters or smaller.
• Stage II: In stage II medullary thyroid cancer, one of the following is found:
  • cancer is in the thyroid only and the tumor is larger than 2 centimeters; or
  • the tumor is any size and cancer has spread from the thyroid to nearby muscles in the neck.
  
• Stage III: In stage III medullary thyroid cancer, the tumor is any size and cancer may have spread from the thyroid to nearby muscles in the neck. Cancer has spread to lymph nodes on one or both sides of the trachea or larynx.
• Stage IV: Stage IV medullary thyroid cancer is divided into stages IVA, IVB, and IVC.
  • In stage IVA, either of the following is found:
    • the tumor is any size and cancer has spread from the thyroid to soft tissue under the skin, the esophagus, the trachea, the larynx, or the recurrent laryngeal nerve (a nerve that goes to the larynx); cancer may have spread to lymph nodes on one or both sides of the neck; or
    • the tumor is any size and cancer may have spread from the thyroid to nearby muscles in the neck; cancer has spread to lymph nodes on one or both sides of the neck.
    
• In stage IVB, the tumor is any size and cancer has spread to tissue in front of the spine or to the spine or has surrounded the carotid artery or the blood vessels in the area between the lungs. Cancer may have spread to lymph nodes.
• In stage IVC, the tumor is any size and cancer has spread to other parts of the body, such as the lungs or liver. Cancer may have spread to lymph nodes.

Thyroid cancer can recur (come back) after it has been treated.

The cancer may come back in the thyroid or in other parts of the body.