Head & Neck

Thyroid Cancer

Cancer of the thyroid gland is an abnormal growth of cells in the butterfly-shaped gland located in the lower neck (see figure below). The thyroid gland produces hormones that control heart rate, body temperature and metabolism (how quickly food is changed into energy). The four parathyroid glands, which sit on the back of the thyroid, also control the amount of calcium in the blood.

A variety of nodules may develop in the thyroid, some cancerous (malignant), others noncancerous (benign). The primary types of thyroid cancer include papillary carcinoma (the most common), follicular carcinoma, medullary thyroid carcinoma and anaplastic carcinoma. Though it is rare, lymphoma can also occur in the thyroid. Cancerous tumors can metastasize (spread) into nearby tissues and organs or to other parts of the body if left untreated.

Diagnosing Thyroid Cancer

Your doctor may suspect thyroid cancer if he or she feels any lumps, swelling or enlarged lymph nodes in the neck. If thyroid cancer is suspected, tests will be done to confirm the diagnosis.

Staging

Staging is how doctors determine the extent of your cancer, where it is located, and whether it has spread to nearby organs or tissue or to other parts of your body. For thyroid cancer, the TNM (tumor, node, metastasis) classification relates to specific stages depending on the specific type of thyroid cancer. 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 (see staging tables below).

Treatment Options

Your doctor will consider many factors when exploring treatment options, including the stage of disease, the location and size of the tumor and your overall health status. Your doctor will also focus on preserving (as much as possible) the ability to talk, eat and breathe normally. Treatment options also depend on whether the thyroid cancer is primary or recurrent. The most common treatment options for thyroid cancer are surgery, radioactive iodine treatment and radiation therapy. Other treatments include chemotherapy, targeted therapy and immunotherapy. You should talk to your health care team about the goal of treatment — whether the goal is to cure the cancer or to keep the cancer under control and relieve symptoms. Understanding the goal, as well as the benefits and risks of each option, will help you become better informed for making shared treatment decisions with your doctor.

Surgery

Surgery to remove all or most of the thyroid gland 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 beyond the thyroid. In some low-risk patients, only half of the thyroid needs to be removed; this procedure is called 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.

Radioactive Iodine Treatment

Radioactive iodine treatment involves giving radioactive iodine (I-131) in liquid or pill form. Because the thyroid gland absorbs iodine, the radioactive iodine will concentrate in the thyroid gland, 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. Radioactive iodine treatment may also be used after surgery if part of the thyroid gland remains.

Radiation therapy

Radiation therapy is sometimes recommended if the cancer has spread to the bones and after surgery if all of the cancer could not be removed. This treatment is more often used as part of treatment for medullary and anaplastic thyroid cancer. With this type of treatment, known as external-beam radiation therapy, a machine delivers high-energy beams of radiation, usually X-rays or gamma rays, at specific points of the body to destroy cancer cells. Radiation therapy is usually given for about six weeks, once a day for 15 to 30 minutes, five days a week.

Chemotherapy

Chemotherapy drugs kill cells that divide quickly, such as cancer cells. Chemotherapy is considered a systemic treatment because the chemotherapy drugs travel throughout the body in the bloodstream. Chemotherapy is given in cycles, and treatment may involve the use of a single drug or multiple drugs in combination. This treatment may be used if surgery and radiation therapy are not successful.

Immunotherapy

Immunotherapy uses the body’s own immune system to slow and kill cancer cells. With this treatment approach, substances – made either by the body or in a laboratory – are used to identify cancer cells as a threat and target them for destruction. Immunotherapy may be used for advanced cancers that did not respond to standard treatment.

Targeted Therapy

Targeted therapy drugs work by targeting specific proteins and genes that help cancer cells grow. This type of treatment can be given as a pill to patients with medullary thyroid cancer. Other 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.

Other types of immunotherapy and targeted therapy are being evaluated in clinical trials. Ask your doctor or other member of your health care team if a clinical trial is an option for you.

Classifying 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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