Diagnosing and Treating Thyroid Cancer

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Thyroid cancer is cancer that starts in cells in your thyroid gland.

Most thyroid cancers can be cured if caught before they spread to other body parts.

This article describes thyroid cancer symptoms, causes, diagnosis, spread, and treatment. It also discusses life after thyroid cancer and disease outlook.

thyroid test

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Thyroid Cancer Symptoms

Early-stage thyroid cancer often occurs without symptoms. It is usually discovered by chance during a routine exam or an imaging test for unrelated reasons.

The time between the onset of thyroid cancer and the appearance of symptoms varies by individual and type of cancer. Papillary thyroid cancer can grow over several years before it causes recognizable symptoms. Other types of thyroid cancer, like anaplastic thyroid cancer, cause a large lump that appears suddenly or develops over a few weeks or months.

Symptoms of thyroid cancer include the following:

Most common:

  • A growth (nodule) that appears as a visible lump on your neck

Less common:

Can You Show Early Signs of Thyroid Cancer?

It's possible, though uncommon, to show early signs of thyroid cancer.

The most common sign of thyroid cancer is a new lump or enlargement in your neck. It rarely causes symptoms and is often discovered by chance. Depending on your type of cancer and your unique situation, this sign can occur early or later in the course of the disease.

Types of Thyroid Cancer

Several types of thyroid cancer exist. Some are more aggressive than others. The three main types of thyroid cancer are differentiated, medullary, and anaplastic, as follows:


  • Includes papillary, follicular, and Hürthle cell thyroid cancer
  • Slow-growing and highly curable.
  • Includes 80% of thyroid cancers (follicular, papillary, and Hürthle cell).


  • Includes sporadic MTC and familial MTC
  • Hard to find and hard to treat
  • Develops from the C cells of the thyroid gland, which make calcitonin (a hormone that controls calcium levels in your blood)

Anaplastic (undifferentiated):

  • Rare and hard to treat
  • Often metastasizes (spreads) quickly to your neck and other parts of the body
  • Cells often don't resemble normal thyroid cells

What Causes Thyroid Cancer?

Thyroid cancer occurs when the DNA that controls the natural cell growth cycle becomes damaged. The damaged thyroid cells grow out of control and live longer than they should. As they increase in number, the damaged cells gather and form tumors in your thyroid.

As the number of damaged cells grows, thyroid cancer spreads (metastasize) to other organs.

The exact cause of most thyroid cancers is not known. However, there is evidence that external radiation may cause damage that triggers abnormal cell growth. This can come from the following sources:

  • Prior radiation therapy of the head and neck regions
  • Exposure to atomic weapons tests or nuclear power plant accidents

While anyone can develop thyroid cancer, having the following risk factors can increase your chances of being diagnosed with the disease:

  • Being a woman
  • Being between 25 and 65 years old
  • Being of Asian descent
  • Prior exposure to radiation of the neck and head.
  • Having a family history of thyroid cancer
  • Having certain genetic conditions, like familial medullary thyroid cancer, multiple endocrine neoplasia type 2A syndrome, and multiple endocrine neoplasia type 2B syndrome
  • Being overweight or having obesity
  • Getting too much or too little iodine from your diet

How Is Thyroid Cancer Diagnosed?

It is common to receive a diagnosis of thyroid cancer before you notice symptoms. However, you can improve your chances of getting the earliest possible diagnosis by doing a thyroid swallowing test at home to check for lumps or enlargements.

If you find a lump, consult your healthcare provider. Diagnosing thyroid cancer involves the following procedures:

Physical exam: During a physical exam, your healthcare provider will take a complete medical history, including details about your symptoms, risk factors, and other medical conditions. Your physical exam will include attention to your neck and the presence of lumps or enlarged lymph nodes in your neck.

Imaging tests:

Fine needle aspiration biopsy of your thyroid (FNA): Necessary for the diagnosis of thyroid cancer, it involves the extraction of a sample of tissue from the tumor for examination at a lab. However, FNA is not always needed for diagnosis. Sometimes a nodule that is large—greater than 4 centimeters (cm)—can have a negative FNA but still be concerning enough to harbor cancer that surgery is required for definitive diagnosis,

Thyroid Cancer Stages: How It Spreads

Thyroid cancer stages are used to define if and how much your thyroid cancer has developed and spread. Thyroid cancer can spread through your lymph system or your blood.

The details used to determine your treatment plan. It is based on criteria set by the American Joint Committee on Cancer (AJCC) and uses the following factors labeled as "TNM":

  • T (tumor): The extent and size of your thyroid tumor
  • N (node): The involvement of nearby lymph nodes
  • M (metastasis): The spread of thyroid cancer to other organs

Thyroid cancer stages are based on these factors:

Stage 1:

  • Primary tumor of 2 cm or smaller (less than 1 inch wide)
  • No spread outside the thyroid

Stage 2:

  • Primary tumor of 2 cm to 4 cm in diameter with no spread of cancer
  • Or, primary tumor that's larger than 4 cm in diameter or has started to grow outside the thyroid without spreading to the lymph nodes or other parts of your body (medullary thyroid cancer only)

Stage 3:

  • Primary tumor larger than 4 cm or has grown outside your thyroid, but has not spread to nearby lymph nodes or beyond (differentiated cancers only)
  • Or, primary tumor of any size or growing outside your thyroid that has spread to lymph nodes in your neck but not elsewhere

Stage 4:

  • Stage 4A: Cancer that has grown beyond the thyroid gland and may have spread to nearby tissue or into your neck and upper check lymph nodes but not to distant organs
  • Stage 4B: Cancer that's spread into your spine or nearby blood vessels with or without affecting your lymph nodes, but not distant organs
  • Stage 4C: Cancer that's spread to distant organs

Stage 4 anaplastic thyroid cancer:

  • Stage 4A: Primary tumor that is contained within your thyroid gland with or without spread to nearby lymph nodes but not to distant organs
  • Stage 4B: Primary tumor that has spread outside your thyroid gland and cancer cells may or may not be in regional lymph nodes but not distant sites
  • Stage 4C: Cancer cells that have spread to more distant parts of your body

The stage of your thyroid cancer is set at diagnosis and does not change, even if your tumor changes during treatment.

The time it takes your thyroid cancer to spread depends on the type of thyroid cancer. Differentiated thyroid cancers spread slowly over months or years. Other types of thyroid cancer are usually more aggressive and can spread in a matter of weeks.

Thyroid Cancer vs. Thyroid Disease

Changes in the production of your thyroid hormone can have different effects. Thyroid cancer is a growth in your thyroid gland. Certain types of thyroid cancer can spread to other parts of your body and cause serious side effects.

Thyroid disease involves a change to your thyroid cells without cancer. These conditions do not spread to other parts of your body. They are not life-threatening.

Thyroid Cancer Treatment

Depending on the stage of your cancer and other factors, including age, type of thyroid cancer, and general health. Your healthcare provider may advise one or more of the following treatments:

Watchful waiting: Watchful waiting involves regular monitoring of your condition by a healthcare provider.

Targeted therapy: Targeted therapy uses drugs that identify and attack certain cells that support tumor growth.

Thyroid hormone therapy: Thyroid hormone therapy blocks or removes thyroid hormones to stop cancer cells from growing.

Chemotherapy: Chemotherapy uses drugs to slow or kill cancer cells. These drugs may be administered orally or by injection.

Radiation therapy: Radiation therapy involves the use of high-energy X-rays or other radiation to kill cancer cells using external or internal treatments.

Surgery: Surgery is the most common treatment for thyroid cancer involves one of the following procedures:

  • Lobectomy: Removal of a lobe that contains thyroid cancer
  • Near-total thyroidectomy: Removal of all but a small part of the thyroid
  • Total thyroidectomy: Removal of the entire thyroid
  • Tracheostomy: Surgery to create an opening (stoma) into your windpipe when breathing is problematic

Side Effects of Thyroid Cancer Treatment

Thyroid cancer treatments affect everyone differently. You may experience the following side effects from the following therapies:

Hormone therapy:


  • Hair loss
  • Mouth sores
  • Loss of appetite
  • Nausea and vomiting
  • Diarrhea
  • Increased risk of infection
  • Easy bruising
  • Fatigue

Radioactive iodine therapy:

Radiation therapy:

  • Dry mouth and throat
  • Hoarseness
  • Swallowing difficulties
  • Fatigue

Surgery: Postsurgical requirement to take lifetime medications to replace thyroid hormones and maintain proper function of your metabolism, digestion, muscle control, bone maintenance, and brain development

Can You Prevent Thyroid Cancer?

It's not possible to prevent thyroid cancer, but you may be able to reduce your risk of getting the disease by following these strategies:

  • Request a thyroid collar to wear during a dental X-ray or X-rays involving your head, neck, chest, and spine to protect these areas from radiation exposure.
  • Perform regular thyroid neck checks to find thyroid problems in their earliest stages when treatment can be most successful.
  • Talk to your healthcare provider about genetic testing if you have a family history of thyroid cancer.
  • Some people inherit an abnormal gene (a mutation) that increases their risk for medullary thyroid cancer. Talk to your healthcare provider about removing your thyroid as a prophylactic (preventive) step if you have the gene that causes medullary thyroid cancer.
  • Work to establish and maintain a healthy body weight.
  • While it is not a common concern in a healthy U.S. diet, avoid making changes that significantly reduce or increase your consumption of iodine.

Life After Thyroid Cancer

Everyone has a unique experience with thyroid cancer. For most people, treatment provides a cure. For others, thyroid cancer may never go away completely. In either situation, it is normal to worry about recurrence and your future.

Your healthcare provider can help you determine how often you will require office visits and follow-up testing to ensure you remain as healthy as possible after therapy. Many thyroid cancer survivors also benefit from the emotional support available via online or local cancer support groups.

If your thyroid was damaged or removed during treatment for thyroid cancer, you may have symptoms of hypothyroidism (underactive thyroid). These symptoms include the following:

  • Fatigue
  • Trouble tolerating cold temperatures
  • Weight gain
  • Joint and muscle pain
  • Dry, thinning hair or dry skin
  • Irregular or heavy menstrual periods
  • Fertility problems
  • Slowed heart rates
  • Depression

The good news is that hypothyroidism can be completely controlled by replacing the amount of thyroid hormone your thyroid can't produce. Hypothyroidism is treated with a prescription oral thyroid hormone preparation. The first-line treatment is Synthroid (levothyroxine), a synthetic version of the hormone thyroxine (T4).

Outlook for Thyroid Cancer

The outlook for thyroid cancer is generally positive for most people. However, everyone has a unique experience with thyroid cancer. Factors like the extent of thyroid cancer, its spread to other areas, and how it reacts to treatment affect your outlook.

Your healthcare provider formulates a prognosis based on your disease characteristics to determine your recovery or survival. Your outlook is calculated on the experiences of large groups of people over many years, not individual cases. Despite your prognosis, your experience may differ due to your unique characteristics.

Thyroid cancer diagnosed and treated in the localized stage, before thyroid cancer spreads, has the best chances of treatment success. Based on data from the Surveillance, Epidemiology, and End Results (SEER) database by the National Cancer Institute, thyroid cancer has the following five-year survival rates that vary by type of cancer:

Papillary thyroid cancer five-year relative survival rates:

  • Localized (no spread): greater than 99.5%
  • Regional (spread to nearby structures): 99%
  • Distant (spread to distant parts of the body): 74%

Follicular thyroid cancer five-year relative survival rates:

  • Localized: greater than 99.5%
  • Regional: 98%
  • Distant: 67%

Medullary thyroid cancer five-year relative survival rates:

  • Localized: greater than 99.5%
  • Regional: 92%
  • Distant: 43%

Anaplastic thyroid cancer five-year relative survival rates:

  • Localized: 39%
  • Regional: 11%
  • Distant: 4%
12 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  2. MD Anderson Cancer Center. Can you have thyroid cancer without knowing?

  3. American Thyroid Association. Thyroid cancer (papillary and follicular.

  4. American Cancer Society. What is thyroid cancer?

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By Anna Giorgi
Anna Zernone Giorgi is a writer who specializes in health and lifestyle topics. Her experience includes over 25 years of writing on health and wellness-related subjects for consumers and medical professionals, in addition to holding positions in healthcare communications.