Thyroid cancer: Full guide

What is thyroid cancer?

The thyroid is a small, butterfly-shaped gland at the front of your neck. It makes hormones that control how your body uses energy. Thyroid cancer starts when cells in this gland grow out of control.

It often shows up as a lump (nodule) in the neck. Many lumps are found by chance on a scan done for another reason. Most thyroid nodules are not cancer.

Thyroid cancer is more common in women. Radiation to the neck, especially in childhood, raises the risk. A few people have an inherited gene change that raises their risk.

There are several types. The most common types grow slowly and are very treatable. A few rare types act very differently. Knowing your type is one of the first steps, and your care team will explain what it means for you.

Types

Papillary thyroid cancer

The most common type, making up most thyroid cancers. It usually grows slowly. It may spread to lymph nodes in the neck, but it is still very treatable.

Follicular thyroid cancer

The second most common type. It also usually grows slowly. It is more likely than papillary cancer to spread through the blood to the lungs or bones.

Oncocytic (Hurthle cell) carcinoma

A less common type that is related to follicular cancer. It may not take up radioactive iodine as well as other types.

Differentiated thyroid cancer

A group name for papillary, follicular, and oncocytic cancers. These cells still look and act a lot like normal thyroid cells. They are often treated with surgery, and sometimes radioactive iodine.

Medullary thyroid cancer

A less common type that starts in C cells, which make a hormone called calcitonin. About 1 in 5 cases runs in families because of a RET gene change. Radioactive iodine does not work for this type.

Anaplastic thyroid cancer

A rare type that grows very fast. It needs care right away at a center with experience. Quick gene testing can find options like targeted pills.

Poorly differentiated thyroid cancer

A rare type that is in between the slow-growing types and anaplastic cancer. It may grow faster and need more treatment.

Tests you may have

Neck ultrasound

Uses sound waves to make pictures of the thyroid and nearby lymph nodes. It shows the size and features of a nodule. It is also used to check on you after treatment.

Fine needle aspiration (FNA) biopsy

A thin needle takes cells from the nodule, often guided by ultrasound. It is the best test to find out if a nodule is cancer. It is done in the office and is usually quick.

Molecular testing of the nodule

If the biopsy result is unclear, the cells can be tested for gene changes. This helps tell how likely the nodule is to be cancer.

Thyroid blood tests (TSH)

TSH is a hormone from the brain that tells the thyroid to work. It is checked at the start and is used to guide your thyroid hormone pill later.

Thyroglobulin

A protein made by thyroid cells. After surgery and radioactive iodine, it works as a tumor marker. A rising level can be a sign the cancer has come back.

Calcitonin and CEA

Blood tests used for medullary thyroid cancer. They help show how much cancer there is and are used to watch it over time.

Radioactive iodine scan

You take a small amount of radioactive iodine, and a camera shows where it goes. It can find thyroid tissue or cancer that takes up iodine.

CT, MRI, or PET scans

These scans check for cancer that has spread beyond the neck. They are used more often for larger or faster-growing cancers.

Voice box check

A doctor may look at your vocal cords with a small camera before or after surgery. This checks the nerves that control your voice.

What the stage means

The stage tells how big the cancer is and how far it has spread. For thyroid cancer, age matters too.

For papillary and follicular cancer, people under 55 are only stage 1 or 2, even if the cancer has spread. This is because younger people tend to do very well.

Doctors also use a risk level (low, intermediate, or high) to plan treatment. This tells how likely the cancer is to come back.

Stage 1

The cancer is small or, in people under 55, has not spread to distant organs. Most people with stage 1 do very well after treatment.

Stage 2

In people under 55, the cancer has spread to distant places like the lungs or bones. In people 55 and older, the tumor is larger or has spread to nearby lymph nodes.

Stage 3

Usually in people 55 and older. The cancer has grown into nearby tissues like the voice box, windpipe, or food pipe.

Stage 4

Usually in people 55 and older. The cancer has grown more deeply in the neck or spread to distant organs. All anaplastic thyroid cancers are called stage 4.

Low risk

Smaller cancers that stay in the thyroid. Surgery alone is often enough. Radioactive iodine is often not needed.

Intermediate or high risk

Cancers that spread to lymph nodes, grew outside the thyroid, or spread farther. These may need more surgery, radioactive iodine, and closer follow-up.

Tumor markers and gene tests

Blood markers help your team watch for cancer after treatment. Gene tests on the tumor matter most when the cancer is advanced or does not respond to radioactive iodine.

For medullary thyroid cancer, a blood test for an inherited RET change is advised for everyone. If you have it, your family members can be tested too.

Thyroglobulin

A blood marker for papillary and follicular cancer after treatment. It is checked along with thyroglobulin antibodies, which can make the test less accurate.

Calcitonin and CEA

Blood markers for medullary thyroid cancer. How fast they rise helps show how fast the cancer is growing.

BRAF V600E

A common gene change in papillary cancer and in some anaplastic cancers. Targeted pills that block BRAF can work very well, especially in anaplastic cancer.

RET

A gene change found in medullary cancer and some papillary cancers. Pills that block RET can work very well. An inherited RET change can cause a syndrome called MEN2.

NTRK and ALK

Rare gene changes called fusions. Targeted pills are available for each.

RAS

A gene change often seen in follicular cancers. It can help when a biopsy result is unclear.

Inherited gene testing

Some families carry gene changes that raise thyroid cancer risk, such as RET, APC, or PTEN. A genetic counselor can help you and your family understand testing.

Main treatments

Lobectomy

Surgery to remove half of the thyroid. It is often used for small, low-risk cancers. Some people do not need a thyroid hormone pill afterward.

Total thyroidectomy

Surgery to remove the whole thyroid. It is used for larger cancers, cancers on both sides, or cancers that have spread. You will need a thyroid hormone pill every day for life.

Neck dissection

Surgery to remove lymph nodes in the neck that have or may have cancer. It is common in medullary cancer and when nodes are known to be involved.

Radioactive iodine (RAI)

A pill or liquid with radioactive iodine. Thyroid cells take it up and are destroyed, while most other cells are not affected. It is used for some papillary and follicular cancers, mostly higher-risk ones. Many low-risk people do not need it.

Thyroid hormone pill and TSH suppression

Levothyroxine replaces the hormone your thyroid made. For some people, a higher amount is used to keep TSH low, which can slow cancer growth. Your team balances this against effects on the heart and bones.

Active surveillance

Some very small, low-risk papillary cancers can be watched closely with ultrasound instead of surgery right away. Ask if this fits you.

Targeted pills

Pills that block signals cancer cells need to grow. They are used for advanced cancers that no longer respond to radioactive iodine, and for advanced medullary or anaplastic cancer. Some block many targets, and some block one gene change like RET or BRAF.

External beam radiation

High-energy beams aimed at the neck or at spots of spread. It is used for some advanced or anaplastic cancers, or to ease pain.

Clinical trials

Research studies that test new treatments. They are an important option for advanced thyroid cancer. Ask if a trial is right for you.

Common side effects and what helps

Hoarse voice

Surgery can bruise or irritate a nerve to the voice box. Most voice changes get better over weeks to months. Tell your team if it does not improve.

Low calcium after surgery

Small glands next to the thyroid control calcium. They can be stunned by surgery. Tingling in the lips, fingers, or toes, or muscle cramps, can be a sign. Your team may give calcium pills.

Feeling tired or off on thyroid hormone

It can take time to find the right amount of thyroid hormone. Take it at the same time each day on an empty stomach. Blood tests guide changes.

Dry mouth and salivary gland swelling

Radioactive iodine can affect the salivary glands. Drink plenty of water. Ask your team whether sour candy or massage might help.

Low-iodine diet

You may need to avoid foods high in iodine, like iodized salt, dairy, and seafood, for a short time before RAI. Ask for a list and a dietitian if you need help.

Radiation safety after RAI

For a few days you will need to keep distance from others, especially children and pregnant people. Your team will give you clear rules to follow.

High blood pressure

Common with some targeted pills. Check your blood pressure at home as your team advises. Medicines can control it.

Diarrhea, low appetite, and weight loss

Common with targeted pills. Drink fluids and eat small meals. Your team can give medicine and may adjust your treatment.

Fatigue

Feeling tired is common with targeted pills. Light activity like short walks can help. Rest when you need to.

Living with and after thyroid cancer

Most people with thyroid cancer do very well. After treatment, you will have regular checkups, blood tests, and neck ultrasounds. These look for any sign the cancer has come back.

If your whole thyroid was removed, you will take a thyroid hormone pill every day for life. Do not skip doses. Tell your team about other pills, like calcium or iron, which can block it if taken at the same time.

After radioactive iodine, people are advised to wait at least 6 months before trying to get pregnant. Breastfeeding must stop before RAI. Talk with your team about family planning.

Some people feel that thyroid cancer is called the good cancer. That can feel unfair. Any cancer is hard, and your feelings are real. Support groups and counselors can help.

If you have medullary thyroid cancer with an inherited RET change, family members should be offered testing. Early surgery can prevent cancer in children who carry the gene.