What is Thyroid Cancer?

Thyroid cancer is a malignant growth or tumor in the thyroid. It is the most common cancer of the endocrine system, the system of glands throughout the body that produce hormones.

Thyroid cancer occurs in both men and women but is almost three times more common in women than in men. It can occur at any age.1

Thyroid cancer represents 3.1% of all new cancers in the United States1. The number of new cases of thyroid cancer is increasing at a faster rate than any other type of cancer.2

Thyroid cancer represents 3.1% of all new cancer cases in the United States1

3.1% of new cancer cases are thyroid cancer

Percent of new cases of thyroid cancer by age group1

estimated number of new thyroid cancer cases by age group 

There is a high treatment success rate for most types of thyroid cancer. When diagnosed and treated early, 98% of patients with thyroid cancer survive for at least 5 years.1,3

Despite high treatment success, it is important to know that up to one-third of thyroid cancers can come back. This can sometimes happen even decades after the first treatment.4 For this reason, thyroid cancer requires long-term monitoring to:

  • make sure that the cancer has not come back
  • begin treatment right away if it has returned.

Survival of people with well-differentiated thyroid cancer1

thyroid cancer survival rate

Different Types of Thyroid Cancer

Not all thyroid cancers are the same. There are four main types of thyroid cancer:2

  • Papillary
  • Follicular
  • Medullary
  • Anaplastic

Papillary and follicular cancers, often referred to as “well-differentiated” thyroid cancers (WDTC), are the most common. Together, they account for about 90% of thyroid cancers.

Prognosis and Outcomes for Patients with Thyroid Cancer

The prognosis for a patient with thyroid cancer depends on several factors, including:

  • the type of thyroid cancer,
  • whether the disease has spread to other parts of the body, and
  • the patient’s age at diagnosis.

Many cases of thyroid cancer can be found early. In fact, most thyroid cancers are now found much earlier than in the past and can be treated successfully.3 To achieve the best outcome, appropriate treatment and commitment to long-term monitoring are important.

Generally, the prognosis, or long-term outlook, for patients diagnosed with well-differentiated thyroid cancer is very good. With regular checkups and long-term monitoring, the 5-year survival rate is over 98%.1 The other types of thyroid cancer, medullary and anaplastic, are much less common, and are more difficult to treat effectively.2

Different types of thyroid cancer2,5

Type Average Age at Diagnosis Prognosis at Time of Diagnosis
Papillary 30-50 Excellent
Follicular 40-60 Good
Medullary 40-50 Variable, dependent on stage at diagnosis
Anaplastic >65 Very poor

What Causes Thyroid Cancer?

It is not clear what causes thyroid cancer. There are certain factors that may lead to a higher risk of getting thyroid cancer. These include:6

  • Gender - thyroid cancers are more common in women
  • Age - women are most likely to get it in their 40s or 50s, while men are more likely to get it in their 60s or 70s
  • A diet low in iodine (this is rare in the US)
  • Radiation exposure - the risk is highest if exposure occurs in childhood
  • Family history - having a parent, brother, sister, or child with thyroid cancer increases your risk of thyroid cancer
  • Certain genetic conditions


Thyroid Cancer Glossary

Low-Iodine Diet

My Doctor Discussion Guide

My Doctor Discussion Guide

More Resources

Thyrogen® (thyrotropin alfa for injection) 0.9 mg/mL after reconstitution


Diagnostic: Thyrogen is used to help identify thyroid disease by testing the blood for a hormone called thyroglobulin in the follow up of patients with a certain type of thyroid cancer known as well differentiated thyroid cancer. It is used with or without a radiology test using a form of iodine.

Limitations of Use:

The effect of Thyrogen on long term thyroid cancer outcomes has not been determined.

When Thyrogen is used to help detect thyroid cancer, there is still a chance all or parts of the cancer could be missed.

Ablation: Thyrogen is also used to help patients prepare for treatment with a form of iodine to remove leftover thyroid tissue in patients who have had surgery to take out the entire thyroid gland for patients with well differentiated thyroid cancer who do not have signs of thyroid cancer which has spread to other parts of the body.

Limitations of Use:

In a study of people being prepared for treatment with a form of iodine after thyroid surgery, results were similar between those who received Thyrogen and those who stopped taking their thyroid hormone. Researchers do not know if results would be similar over a longer period of time.


There have been reports of events that led to death in patients who not had surgery to have their thyroid gland removed, and in patients with thyroid cancer cells that have spread to other parts of the body.

Patients over 65 years old with large amounts of leftover thyroid tissue after surgery, or with a history of heart disease, should discuss with their physicians the risks and benefits of Thyrogen.

Thyrogen can be administered in the hospital for patients at risk for complications from Thyrogen administration.

Since Thyrogen was first approved for use, there have been reports of central nervous system problems such as stroke in young women who have a higher chance of having a stroke, and weakness on one side of the body.

Patients should remain hydrated prior to treatment with Thyrogen.

Leftover thyroid tissue after surgery and cancer cells that have spread to other parts of the body can quickly grow and become painful after Thyrogen administration.

Patients with cancer cells near their windpipe, in their central nervous system, or in their lungs may need treatment with a glucocorticoid (a medication to help prevent an increase in the size of the cancer cells before using Thyrogen.)


In clinical studies, the most common side effects reported were nausea and headache.


Pregnant patients: Thyrogen should be given to a pregnant woman only if the doctor thinks there is a clear need for it.

Breastfeeding patients: It is not known whether Thyrogen can appear in human milk. Breastfeeding women should discuss the benefits and risks of Thyrogen with their physician.

Children: Safety and effectiveness in young patients (under the age of 18) have not been established.

Elderly: Studies do not show a difference in the safety and effectiveness of Thyrogen between adult patients less than 65 years and those over 65 years of age.

Patients with kidney disease: Thyrogen exits the body much slower in dialysis patients and can lead to longer high TSH levels.

You are encouraged to report negative side effects of prescription drugs to the FDA. Visit www.fda.gov/medwatch, or call 1-800-FDA-1088.


  1. SEER Thyroid Cancer 2018. https://seer.cancer.gov/statfacts/html/thyro.html. Accessed January 2019.
  2. American Cancer Society. Thyroid Cancer. 2018. https://www.cancer.org/content/dam/CRC/PDF/Public/8853.00.pdf. Accessed January 2019.
  3. Brown AP, Chen J, Hitchcock YJ, Szabo A, Shrieve DC, Tward JD 2008 The risk of second primary malignancies up to three decades after the treatment of differentiated thyroid cancer. J Clin Endocrinol Metab 93:504–515.
  4. American Cancer Society. Thyroid Cancer Early Detection, Diagnosis, and Staging. 2016. https://www.cancer.org/content/dam/CRC/PDF/Public/8855.00.pdf. Accessed January 2019.
  5. Al-Noury MK, Almuhayawi SM, Alghamdi KB, Al-Noury KI. Preoperative imaging modalities to predict the risk of regional nodal recurrence in well-differentiated thyroid cancers. Int Arch Otorhinolaryngol. 2015;19:116-120.
  6. Brady B. Endocrineweb. Thyroid Cancer Guide - Incidence and Types of Thyroid Cancer. 2018. https://www.endocrineweb.com/guides/thyroid-cancer/incidence-types-thyroid-cancer. Accessed January 2019.
  7. American Cancer Society. Thyroid Cancer Causes, Risk Factors, and Prevention. 2016. https://www.cancer.org/content/dam/CRC/PDF/Public/8854.00.pdf. Accessed January 2019.
  8. Kitahara Cari M. Sosa Julie A. The changing incidence of thyroid cancer. Nature reviews Endocrinology. 2016; 12: 646-653.