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Merck Manual
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Home /
Quick Facts: Hormonal and Metabolic Disorders /
Thyroid Gland Disorders /
... /
Thyroid Cancer /
IN THIS TOPIC

What is thyroid cancer?

What are the types of thyroid cancer?

What causes thyroid cancer?

What are the symptoms of thyroid cancer?

How can doctors tell if I have thyroid cancer?

How do doctors treat thyroid cancer?

OTHER TOPICS IN THIS CHAPTER

Thyroid Gland Disorders
Overview of the Thyroid Gland
Hyperthyroidism
Hypothyroidism
Hashimoto Thyroiditis
Thyroid Cancer

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Quick Facts

Thyroid Cancer

By

The Manual's Editorial Staff

Last full review/revision Jul 2020| Content last modified Jul 2020
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Topic Resources

Your thyroid is a gland below the Adam’s apple in your neck.

Your thyroid releases thyroid hormones. The hormones control how fast your body’s chemical functions work (metabolic rate). Almost every cell in your body needs thyroid hormones. Among many other things, thyroid hormones help control:

  • How fast you burn calories

  • How fast your heart beats

  • Your body temperature

Locating the Thyroid Gland

Locating the Thyroid Gland

What is thyroid cancer?

Thyroid cancer is cancer in your thyroid.

  • The first sign of thyroid cancer is usually a painless lump in your neck

  • There are 4 main kinds of thyroid cancer

  • Thyroid cancer is more common in women and people treated with radiation as a child

  • Doctors treat different types of thyroid cancer in different ways

  • The most common type of thyroid cancer is often curable

What are the types of thyroid cancer?

There are 4 types of thyroid cancer:

  • Papillary (the most common and easy to cure)

  • Follicular

  • Medullary

  • Anaplastic (rarest and most deadly)

What causes thyroid cancer?

Doctors don't know what causes thyroid cancer. It's more common in women and people who were treated with radiation to their head, neck, or chest as a child. Some less common types of thyroid cancer run in families.

What are the symptoms of thyroid cancer?

A painless lump in your neck is usually the first sign of thyroid cancer.

Sometimes a larger cancer may press on your neck, causing:

  • Feeling of fullness in your neck

  • A hoarse voice

  • Cough

  • Difficulty breathing

Thyroid cancers don't usually make thyroid hormones so you aren't likely to have symptoms of hyperthyroidism (too much thyroid hormone).

How can doctors tell if I have thyroid cancer?

After doctors find a lump in your neck, they may do:

  • Blood tests to measure thyroid function

  • Ultrasound

  • Biopsy (a sample of the lump taken with a small needle and examined under a microscope)

How do doctors treat thyroid cancer?

Treatment depends on the type of cancer and whether it has spread, but doctors often:

  • Do surgery to remove some or all of your thyroid gland

After surgery, you may get radioactive iodine or radiation therapy to get rid of any cancer left.

After treatment, you'll have little or no thyroid function, so you will have to take:

  • Thyroid hormone pills

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© 2020 Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, NJ, USA)
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