Head & Neck

Thyroid Cancer

Thyroid cancer forms in the tissues of the butterfly-shaped thyroid gland located in the lower neck. The thyroid produces hormones that control heart rate, body temperature and metabolism (how quickly food is changed into energy). The four parathyroid glands, which are small pea-sized organs that sit on the back of the thyroid, also produce hormones that control blood calcium levels.

There are four primary types of thyroid cancer: papillary (the most common), follicular, medullary and anaplastic. Papillary and follicular thyroid cancers are sometimes referred to as differentiated thyroid cancer, and medullary and anaplastic thyroid cancer may be referred to as poorly differentiated or undifferentiated thyroid cancer.

After test results help your doctor confirm a diagnosis of thyroid cancer, staging is the next step. For thyroid cancer, the TNM (tumor, node, metastasis) classification relates to specific stages depending on the type of thyroid cancer (see Staging Tables, below). Medullary thyroid cancer is staged from Stage I to Stage IVC. In papillary and follicular thyroid cancers, age is a factor in staging. Disease in people younger than 55 years is diagnosed as either Stage I or II. Disease in people 55 years or older can be staged from Stage I to IVC. All anaplastic cancers are classified as Stage IV because they are a very aggressive type of thyroid cancer.

Common Treatments

The most common treatments for thyroid cancer are surgery, radioactive iodine treatment, radiation therapy and immunotherapy. Other options include chemotherapy and targeted therapy. Talk with your health care team about the goal of treatment — whether it is to cure the cancer or to control the cancer while relieving symptoms. Being on the same page, and understanding the benefits and risks of each option, will help you make more informed treatment decisions with your doctor. (See Treatment Options for general descriptions of each treatment type.)

Surgery

Surgery to remove all or most of the thyroid is the most common treatment for thyroid cancer. In addition to removing the thyroid, your surgeon may also remove lymph nodes in the neck to see if the cancer has spread. In some low-risk patients, only half of the thyroid needs to be removed; this procedure is called a hemithyroidectomy. If the entire thyroid gland is removed, thyroid hormone can no longer be produced in the body. This means that medication must be taken as a replacement for the hormone. This treatment, which can be taken as a pill, is known as thyroid hormone therapy. Taking calcium and vitamin D supplements may also be necessary if the parathyroid gland function is affected by surgery.

Radioactive iodine treatment

Radioactive iodine treatment involves giving radioactive iodine (I-131) in liquid or pill form. It may be used after surgery if part of the thyroid remains. Because the thyroid normally absorbs iodine, the radioactive iodine will concentrate in any remaining thyroid tissue, and the radiation will kill the cancer cells. This treatment is standard of care for papillary or follicular thyroid cancer that has spread to lymph nodes in the neck or other parts of the body.

Radiation therapy

This treatment is more often used as part of treatment for medullary and anaplastic thyroid cancer. External-beam radiation therapy is usually given for about six weeks, once a day for 15 to 30 minutes, five days a week.

Immunotherapy

Immunotherapy may be used for advanced thyroid cancers that did not respond to standard treatment.

Other treatment options

Chemotherapy may be used if surgery and radiation therapy are not successful. Targeted therapy may be given orally to treat medullary thyroid cancer, and some types of targeted therapy drugs may be given to people with papillary or follicular thyroid cancer for whom standard treatment (surgery or radioactive iodine therapy) was not effective. Clinical trials may be another treatment option. Ask your doctor if you are a candidate for a clinical trial, and look for some that may apply to you (see Clinical Trials).

Stages of Thyroid Cancer

Classification Definition
Tumor (T)
TX Primary tumor cannot be assessed.
T0 No evidence of primary tumor.
Anaplastic & Differentiated
T1 Tumor ≤ (not more than) 2 cm in greatest dimension limited to the thyroid.
  T1a Tumor ≤ (not more than) 1 cm in greatest dimension limited to the thyroid.
  T1b Tumor > (more than) 1 cm but ≤ (not more than) 2 cm in greatest dimension limited to the thyroid.
T2 Tumor > (more than) than 2 cm but ≤ (not more than) 4 cm in greatest dimension limited to the thyroid.
T3 Tumor > (more than) 4 cm limited to the thyroid, or gross extrathyroidal extension (extended beyond the thyroid) invading only strap muscles.
  T3a Tumor > (more than) 4 cm limited to the thyroid.
  T3b Gross extrathyroidal extension (extended beyond the thyroid) invading only strap muscles (sternohyoid, sternothyroid, thyrohyoid or omohyoid muscles) from a tumor of any size.
T4 Includes gross extrathyroidal extension (extended beyond the thyroid) beyond the strap muscles.
  T4a Gross extrathyroidal extension (extended beyond the thyroid) invading subcutaneous soft tissues, larynx, trachea, esophagus, or recurrent laryngeal nerve from a tumor of any size.
  T4b Gross extrathyroidal extension (extended beyond the thyroid) invading prevertebral fascia or encasing the carotid artery or mediastinal vessels from a tumor of any size.
Medullary
T1 Tumor is ≤ (not more than) 2 cm in greatest dimension limited to the thyroid.
  T1a Tumor is ≤ (not more than) 1 cm in greatest dimension limited to the thyroid.
  T1b Tumor is > (more than) 1 cm but ≤ (not more than) 2 cm in greatest dimension limited to the thyroid.
T2 Tumor is > (more than) 2 cm but ≤ (not more than) 4 cm in greatest dimension limited to the thyroid.
T3 Tumor is > (more than) 4 cm or with extrathyroidal extension (extended beyond the thyroid).
  T3a Tumor is > (more than) 4 cm in greatest dimension limited to the thyroid.
  T3b Tumor of any size with gross extrathyroidal extension (extended beyond the thyroid) invading only strap muscles (sternohyoid, sternothyroid, thyrohyoid or omohyoid muscles).
T4 Advanced disease.
  T4a Moderately advanced disease; tumor of any size with gross extrathyroidal extension (extended beyond the thyroid) into the nearby tissues of the neck, including subcutaneous soft tissue, larynx, trachea, esophagus or recurrent laryngeal nerve.
  T4b Very advanced disease; tumor of any size with extension toward the spine or into nearby large blood vessels, gross extrathyroidal extension (extended beyond the thyroid) invading the prevertebral fascia, or encasing the carotid artery or mediastinal vessels.
Node (N)
NX Regional lymph nodes cannot be assessed.
N0 No evidence of locoregional lymph node metastasis.
  N0a One or more cytologically (based on fine needle aspiration biopsy) or histologically (based on pathologic analysis of tissues after surgery) confirmed benign lymph nodes.
  N0b No radiologic or clinical evidence of locoregional lymph node metastasis.
N1 Metastasis to regional nodes.
  N1a Metastasis to level VI or VII (pretracheal, paratracheal, or prelaryngeal/Delphian, or upper mediastinal) lymph nodes. This can be unilateral (on one side) or bilateral (on both sides) disease.
  N1b Metastasis to unilateral (on one side), bilateral (on both sides), or contralateral (opposite side of thyroid tumor) lateral lymph nodes (levels I, II, III, IV or V) or retropharyngeal lymph nodes.
Metastasis (M)
M0 No distant metastasis.
M1 Distant metastasis.

Used with permission of the American Joint Committee on Cancer (AJCC), Chicago, Illinois. The original and primary source for this information is the AJCC Cancer Staging Manual, Eighth Edition (2017) published by Springer Science+Business Media.

Staging Anaplastic Thyroid Cancer

Stage T N M
IVA T1 - T3a N0/NX M0
IVB T1 - T3a
T3b, T4
N1
Any N
M0
M0
IVC Any T Any N M1

Staging Differentiated Thyroid Cancer*

Stage T N M
Younger than 55 years
I Any T Any N M0
II Any T Any N M1
55 years or older
I T1, T2 N0, NX M0
II T1, T2
T3a, T3b
N1
Any N
M0
M0
III T4a Any N M0
IVA T4b Any N M0
IVB Any T Any N M1
*Includes papillary, follicular, poorly differentiated and Hurthle cell carcinoma

Staging Medullary Thyroid Cancer

Stage T N M
I T1 N0 M0
II T2, T3 N0 M0
III T1 - T3 N1a M0
IVA T4a
T1 - T3
Any N
N1b
M0
M0
IVB T4b Any N M0
IVC Any T Any N M1
 

Additional Resources

 

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