How is thyroid cancer found?

Many thyroid cancers can be found early. Most early thyroid cancers are found when patients see their doctors because of neck lumps or bumps they have noticed. If you have symptoms such as a lump or swelling in your neck, you should see your doctor right away.

Other cancers are found by the doctor during a routine checkup or when people have ultrasound tests of the neck for other health problems.

Blood tests or thyroid ultrasound can often find changes in the thyroid, but these tests are not used as screening tests for thyroid cancer unless there is a reason (such as family history) to suspect a person is at a higher risk for thyroid cancer.

People with a family history of medullary thyroid cancer (MTC) might have a very high risk for getting this cancer. Most doctors suggest genetic testing for these people when they are young to see if they carry the gene changes linked to MTC. For people who may be at risk but don’t get genetic testing, blood tests can help find MTC at an early stage, when it may still be cured. Thyroid ultrasounds may also be done in high-risk people.

Signs and symptoms of thyroid cancer

Thyroid cancer can cause any of these signs or symptoms:

• A lump in the neck, sometimes growing quickly
• Swelling in the neck
• Pain in the front of the neck, sometimes going up to the ears
• Hoarseness or other voice changes that do not go away
• Trouble swallowing
• Trouble breathing
• A constant cough that is not due to a cold

If you have any of these signs or symptoms, talk to your doctor right away. Many of these symptoms can be caused by other things. Thyroid lumps (nodules) are common and are usually benign. Still, if you have any of these problems, see your doctor right away so the cause can be found and treated, if needed.

Medical history and physical exam

If you have any signs or symptoms that suggest you might have thyroid cancer, your doctor will want to get your complete medical history. You will be asked questions about your possible risk factors, symptoms, and any other health problems or concerns. If someone in your family has had thyroid cancer or certain kinds of tumors (called pheochromocytomas), tell your doctor, as you might be at high risk for this disease.

During the physical exam, your doctor will pay special attention to the size and firmness of your thyroid and any enlarged lymph nodes in your neck.

Biopsy

A final diagnosis of thyroid cancer is made with a biopsy, in which cells from the area of concern are removed and looked at under a microscope. But this might not be the first test done if you have a lump in your neck. The doctor might order other tests first, such as blood tests, an ultrasound exam, or a radioiodine scan to get a better sense of whether you might have thyroid cancer. These tests are described below.

If your doctor thinks a biopsy is needed, the simplest way to find out if a thyroid lump or nodule is cancer is by doing a fine needle aspiration (FNA) biopsy.

This type of biopsy can usually be done in your doctor’s office or clinic. Before the biopsy, medicine may be used to numb the skin over the nodule. Your doctor will then put in a thin, hollow needle into the lump to draw out cells and a few drops of fluid. The doctor usually repeats this 2 or 3 times to take samples from several places. The cells can then be looked at under a microscope to see if they look like cancer.

If a nodule is too small for the doctor to feel, sometimes FNA biopsies can be done using an ultrasound machine to help the doctor find the right place to put the needle.

Sometimes an FNA biopsy will need to be repeated because the samples didn’t contain enough cells. Most FNA biopsies will show that the thyroid nodule is benign. Only about 1 out of every 20 biopsies will clearly show cancer.

Sometimes the test results come back as “suspicious” or “of undetermined significance” if the FNA findings don’t show for sure whether the nodule is cancer or not. If this happens, the doctor may order tests on the sample to see if the cells have certain gene changes. Finding these changes makes thyroid cancer much more likely.

In some cases, another biopsy may be needed to get a better sample. This might include a biopsy using a larger needle or a surgical “open” biopsy to remove the nodule or a larger part of the thyroid gland. This kind of biopsy is done in the hospital while you are in a deep sleep.

Imaging tests

Imaging tests make pictures of the inside of your body. They may be done for a number of reasons:

• To find suspicious areas that might be cancer
• To learn how far cancer may have spread

To help find out if treatment has been workingUltrasound

Ultrasound uses sound waves to create pictures of parts of your body. For this test, a small wand is placed on the skin in front of your thyroid gland. It gives off sound waves and picks up the echoes as they bounce off the thyroid. The echoes are seen as a black and white image on a computer screen. No radiation is used in this test.

This test can help show if thyroid nodules are solid or filled with fluid. (Solid ones are more likely to be cancer.) It can also be used to help guide a biopsy needle into a nodule to take a sample. Ultrasound can also help show whether any nearby lymph nodes are enlarged because the thyroid cancer has spread.

Radioiodine scan

Radioiodine scans can be used to help find out if someone with a lump in the neck might have thyroid cancer. They are also often used in patients with differentiated thyroid cancer to help show if it has spread. (Medullary thyroid cancer cells do not take up iodine, so radioiodine scans are not used for this cancer.)

For this test, a small amount of radioactive iodine is swallowed as a pill or put into a vein. Over time, the iodine is absorbed by the thyroid cells. A special camera is used several hours later to see the radioactivity.

For a thyroid scan, the camera is placed in front of your neck to measure the amount of radiation in the gland. Abnormal areas of the thyroid that have less radioactivity than the surrounding tissue are called cold nodules, and areas that take up more radiation are called hot nodules. Hot nodules usually are not cancer, but cold nodules can be either benign or cancer. So this test by itself can’t diagnose thyroid cancer.

After surgery for thyroid cancer, whole-body radioiodine scans are useful in looking to see if cancer has spread throughout the body.

Radioactive iodine can also be used to treat differentiated thyroid cancer, but it is given in much higher doses. This type of treatment is described in the section, “Radioactive iodine treatment.”

Chest x-ray

If you have thyroid cancer, your chest may be x-rayed to see if cancer has spread to your lungs.

Computed tomography (CT) scan

The CT scan is an x-ray test that gives detailed pictures of your body. The CT scan can help show the place and size of thyroid cancers and whether they have spread to nearby areas. A CT scan can also be used to look for spread into distant organs like the lungs.

A CT scanner has been described as a large donut, with a narrow table in the middle opening. You will need to lie still on the table while the scan is being done. CT scans take longer than regular x-rays, and you might feel a bit confined by the ring while the pictures are being taken.

Instead of taking one picture, like a regular x-ray, a CT scanner takes many pictures as it rotates around you while you lie on a table. A computer then combines these pictures.

Before the test, you may be asked to drink a contrast solution or receive an IV (intravenous) line through which a different contrast dye is put in. This helps better outline structures in your body. You might feel some flushing (a feeling of warmth). Some people are allergic and get hives. Rarely, more serious problems like trouble breathing or low blood pressure can happen. Be sure to tell the doctor if you have any allergies or have ever had any problems from contrast dye used for x-rays.

In some cases, a CT scan can be used to guide a biopsy needle right into a suspected area of cancer spread.

Because the CT contrast dye contains iodine, (which can cause problems with radioiodine scans described above), many doctors prefer MRI scans instead of CT scans.

Magnetic resonance imaging (MRI) scan

Like CT scans, MRI scans can be used to look for cancer in the thyroid or cancer that has spread to other parts of the body. But ultrasound is usually the first choice for looking at the thyroid. MRI scans are helpful in looking at the brain and spinal cord.

MRI scans use radio waves and strong magnets instead of x-rays. A contrast material is often put into a vein before the scan to better show the details.

MRI scans take longer than CT scans — often up to an hour. And you might have to lie inside a narrow tube, which can upset people who don’t like enclosed spaces. Newer, more open MRI machines can sometimes be used instead. The machine also makes buzzing and clicking noises that you may find disturbing. Some centers provide earplugs to block this noise out.

PET (positron emission tomography) scan

For a PET scan, a kind of radioactive sugar is put into the blood. The amount used is very low. Because cancer cells in the body are growing quickly, they absorb more of the sugar than normal cells. After waiting about an hour, you lie on a table in the PET scanner for about 30 minutes while a special camera creates a picture of areas of radioactivity in the body.

This test can be very useful if your thyroid cancer is one that doesn’t take up radioactive iodine. In this case, the PET scan may be able to tell whether the cancer has spread.

Some newer machines are able to do both a PET and CT scan at the same time. This lets the doctor see areas that “light up” on the PET scan in more detail.

Blood tests

Blood tests alone can’t tell if a person has thyroid cancer. But they can help show if the thyroid is working as it should, which may help the doctor decide what other tests may be needed.

Medullary thyroid cancer tests

If medullary thyroid cancer (MTC) is suspected or if you have a family history of the disease, blood tests of calcitonin levels can help look for MTC. Calcitonin is a hormone that helps control how the body uses calcium. This test also is useful in seeing if the cancer has come back after treatment.

People with MTC often have high blood levels of a protein called carcinoembryonic antigen (CEA). Tests for CEA can sometimes help find this cancer.

Tests used with other types of thyroid cancer

Your blood may be tested for levels of thyroid hormones (T3 and T4), thyroid-stimulating hormone (TSH), and thyroglobulin to see if the thyroid is working normally.

These tests can’t tell if you have thyroid cancer, but they may be done during and after cancer treatment to check thyroid function or to help find out if the cancer may have returned.

Other blood tests

You may have other blood tests as well. If you are scheduled for surgery, tests will be done to check your blood cell counts, to look for bleeding problems, and to check your liver and kidney function.

Vocal cord exam

Thyroid tumors can sometimes affect the vocal cords. If you are going to have surgery to treat thyroid cancer, a vocal cord exam probably will be done ahead of time to see if the vocal cords are moving the way they should. For this exam, the doctor looks down the throat at the voice box with special mirrors or with a thin tube with a light and a lens on the end (a laryngoscope).