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Stages of Thyroid Cancer
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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 stage in order 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, 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.
- MRI (magnetic resonance imaging): A procedure that uses a magnet, radio waves, and a computer to make a series of detailed pictures of areas inside the body. This procedure is also called nuclear magnetic resonance imaging (NMRI).
- 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.
- Radioactive iodine scan (RAI scan): A procedure to find areas in the body where thyroid cancer cells may be dividing quickly. Radioactive iodine (RAI) is used because only thyroid cells take up iodine. A very small amount of RAI is swallowed, travels through the blood, and collects in thyroid tissue and thyroid cancer cells anywhere in the body. Abnormal thyroid cells take up less iodine than normal thyroid cells. Areas that do not absorb the iodine normally (cold spots) show up lighter in the picture made by the scan. Cold spots can be either benign (not cancer) or malignant, so more tests are needed to find out if they are cancer. A scan of the whole body may be done to find out the stage of the cancer.
- Lymph node biopsy: The removal of all or part of a lymph node. A pathologist views the tissue under a microscope to look for cancer cells.
- 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 and is detected by a scanner.
- 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.
There are three ways that cancer spreads in the body.
The three ways that cancer spreads in the body are:
- Through tissue. Cancer invades the surrounding normal tissue.
- Through the lymph system. Cancer invades the lymph system and travels through the lymph vessels to other places in the body.
- Through the blood. Cancer invades the veins and capillaries and travels through the blood to other places in the body.
When cancer cells break away from the primary (original) tumor and travel through the lymph or blood to other places in the body, another (secondary) tumor may form. This process is called metastasis. The secondary (metastatic) tumor is the same type of cancer as the primary tumor. For example, if breast cancer spreads to the bones, the cancer cells in the bones are actually breast cancer cells. The disease is metastatic breast cancer, not bone cancer.
The following stages are used for papillary and follicular thyroid cancer in patients younger than 45 years:
Stage I
In stage I papillary and follicular thyroid cancer, the tumor is any size, may be in the thyroid, or 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, cancer has spread from the thyroid to other parts of the body, such as the lungs or bone.
The following stages are used for papillary and follicular thyroid cancer in patients 45 years and older:
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| Pea, peanut, walnut, and lime show tumor sizes. |
Stage I
In stage I papillary and follicular thyroid cancer, cancer is found only in the thyroid and the tumor is 2 centimeters or smaller.
Stage II
In stage II papillary and follicular thyroid cancer, cancer is only in the thyroid and the tumor is larger than 2 centimeters but not larger than 4 centimeters.
Stage III
In stage III papillary and follicular thyroid cancer,
either of the following is found:
- the tumor is larger than 4 centimeters or the tumor is any size and cancer has spread to tissues just outside the thyroid, but not to lymph nodes; or
- the tumor is any size and cancer may have spread to tissues just outside the thyroid and has spread to lymph nodes near the trachea or the larynx (voice box).
Stage IV
Stage IV papillary and follicular thyroid cancer is divided into stages IVA, IVB, and IVC.
The following stages are used for medullary thyroid cancer:
Stage 0
Stage 0 medullary thyroid cancer is found only with a special screening test. No tumor can be found in the thyroid.
Stage I
Stage I medullary thyroid cancer is found only in the thyroid and is 2 centimeters or smaller.
Stage II
Stage II medullary thyroid cancer is only in the thyroid and is larger than 2 centimeters but not larger than 4 centimeters.
Stage III
In stage III medullary thyroid cancer:
Stage IV
Stage IV medullary thyroid cancer is divided into stages IVA, IVB, and IVC.
Anaplastic thyroid cancer is considered stage IV thyroid cancer.
Anaplastic thyroid cancer grows quickly and has usually spread within the neck when it is found. Stage IV anaplastic thyroid cancer is divided into stages IVA, IVB, and IVC.
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