Diagnosing thyroid cancer

Saturday 1 February, 2014

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On this page:  Blood test | Ultrasound | Biopsy | Radioisotope scan | Further scans | Staging thyroid cancer | Prognosis | Which health professionals will I see? | Key points

If your doctor suspects you have thyroid cancer, you will have one or more of the following tests. It’s unlikely you will have all of the tests listed on this page. Some of these tests can also show if the cancer has spread to other parts of your body.

Blood test

Your doctor may do a blood test to check the levels of hormones (such as T3 and T4) and thyroid-stimulating hormone (TSH). A cancerous thyroid can continue to function normally so a blood test may help rule out benign thyroid conditions, such as hypothyroidism or hyperthyroidism. If the blood test results show evidence of hyperthyroidism, you may have a radioisotope scan.

The levels of calcitonin and a protein called thyroglobulin (Tg) may also be checked. High calcitonin levels in the blood can indicate medullary thyroid cancer.


An ultrasound is a type of scan that uses soundwaves to produce a picture of internal organs. If you have a lump in your thyroid, the ultrasound can help the doctor determine if it is solid or fluid-filled.

The doctor will also check if the lump is the size and shape of a typical cancer. The scan can also show if the lymph nodes (small, bean-shaped structures) in your neck are affected.

The ultrasound scan is painless and takes about 15–20 minutes. A gel is spread over your neck, then a handheld device called a transducer is moved over the area. The device sends out soundwaves that echo when they meet something dense, like an organ or tumour. A computer changes these echoes into a picture.


If the doctor feels a nodule or sees it during an ultrasound, you may have a biopsy. This is when some thyroid tissue is removed and sent for examination under a microscope.

A fine needle aspiration is the most common type of biopsy. This is when a thin needle is inserted into your neck and a very small tissue sample is removed from the thyroid. You may be given local anaesthesia (pain relief) and an ultrasound may be used to guide the needle. The doctor usually has to do a few passes with the needle to get an adequate tissue sample.

It’s not always possible to determine the type of nodule with a fine needle aspiration. If the results aren’t clear, the doctor may do a biopsy during a hemi-thyroidectomy procedure.

If thyroid cancer is found, you may need further surgery to remove the rest of your thyroid and possibly some lymph nodes in the neck.

"My initial fine needle biopsy results were inconclusive so I had half of my thyroid removed."

Radioisotope scan

If the blood test shows evidence of an overactive thyroid (hyperthyroidism), you may have a radioisotope scan.

In this test, a small amount of radioactive liquid (such as iodine or technetium) is injected into a vein in your arm. After about 20 minutes, you will be asked to lie under a machine called a gamma camera. The camera measures the amount of radioactive liquid taken up by the thyroid gland.

Normal thyroid cells absorb iodine more quickly than cancer cells. Cells that take up more or a lot of the fluid may be called hyperfunctioning or ‘hot’ nodules and are usually benign. Cells that don’t take up much radioactive fluid are called ‘cold’ nodules – these also usually indicate a benign thyroid condition, but a small number may be cancerous.

A radioisotope scan may be used to detect papillary or follicular thyroid cancer. It isn’t used to find medullary thyroid cancer, as C-cells do not absorb iodine.

A radioisotope scan is painless and causes few side effects. After a diagnostic scan you will not be radioactive and it is safe for you to be with others. If you have the scan after radioactive iodine treatment, you will be slightly radioactive, and you will need to take some precautions to minimise the risk of exposing other people to radiation. Your medical team will talk to you about this.

The radioisotope scan may also be used as a follow-up test to check if there are any cancer cells remaining in your body after surgery or radioactive iodine treatment, or to see if the cancer has come back.

Further scans 

The following scans are used to see if the cancer has spread to other parts of your body. These scans may also be used after a surgical procedure, such as a thyroidectomy.

The scans are painless and are done as a day procedure. Most people are able to go home as soon as the procedure is over.

CT scan

A CT (computerised tomography) scan uses x-ray beams to form a more detailed picture of the inside of the body. You may have a CT scan if your thyroid is enlarged, so your doctor can make sure your windpipe (trachea) is not compressed.

Before the scan, dye may be injected into one of your veins to help create clearer pictures. This may make you feel flushed or hot for a few minutes and may also leave a strange taste in your mouth.

The CT scanner is large and round like a doughnut. You will lie on a table that moves in and out of the scanner. Some people feel afraid of confined spaces (claustrophobic), but the scan usually only takes a few minutes.

The dye used for a CT or MRI scan is called a contrast solution and may contain iodine. If you are allergic to iodine, fish or dyes, let the person performing the scan know in advance.

MRI scan

The MRI (magnetic resonance imaging) scan uses both magnetism and radio waves to build up detailed cross-sectional pictures of the body. You will lie on a table that slides into a metal cylinder – a large magnet – that is open at both ends.

As with a CT scan, a dye may be injected into your veins before the scan.

Some people find lying in the narrow metal cylinder noisy and confining. Let your health care team know if you are uncomfortable or claustrophobic during the scan. They may help you to relax by allowing you to use headphones to listen to music, wear an eye mask or take a mild sedative.

People who have a pacemaker, joint replacement or certain other metallic objects in their body cannot have an MRI due to the potentially damaging effect of the magnet.

PET scan

The PET (positron emission tomography) scan may be used after a thyroidectomy to work out if the cancer has come back. It’s only used occasionally, if the doctor thinks the cancer needs to be viewed in a different way.

Before the scan, you will be asked not to eat or drink for a period of time (fast). During this scan you will be injected with a small amount of radioactive glucose solution. It takes 30–90 minutes for the solution to flow throughout your body.

Your body will then be scanned for concentrated levels of radioactive glucose. Cancer cells show up brighter on the scan because they take up more of the glucose solution than normal cells. The PET scan is usually done on an outpatient basis, however it takes several hours to prepare for and have the scan.

Staging thyroid cancer 

The tests described above help determine whether you have thyroid cancer.

Some tests also show if the cancer has spread to other parts of the body. This is called staging. It helps your doctors recommend the best treatment for you. Most cancers follow a general international staging system known as TNM.

TNM system
T (Tumour) indicates the tumour size
N (Nodes)
indicates whether the lymph nodes are affected
M (Metastasis)
indicates whether the cancer has spread to other parts of the body

Numbers or letters may be used after the T, N and M to provide more details. For example, a T1 tumour is smaller than a T2 tumour. The cancer may be grouped into further stages, based on your age and cancer type.

Doctors will usually explain cancer staging in plain English. If you are confused, ask your doctor or nurse to give you more information.You can also call Cancer Council Helpline 13 11 20 for more information.


Prognosis means the expected outcome of a disease. You may wish to discuss your prognosis and treatment options with your doctor, but it is not possible for any doctor to predict the exact course of the disease. Instead, your doctor can give you an idea of what may happen, based on statistics and common issues that affect people with thyroid cancer.

The type of thyroid cancer you have, test results, the rate of tumour growth, how well you respond to treatment are all important factors in assessing your prognosis. Your doctor will also consider your age, fitness and medical history.

The most common types of thyroid cancer (papillary and follicular) have a very good long-term prognosis, especially if the cancer is found only in the thyroid or is confined to the nearby lymph nodes in the neck. Even if it has spread (metastasised), the outcome can still be very good.

Five-year survival rates

Most research studies monitor patients up to five years after treatment, so the most common way to measure average survival is the five-year survival rate. This statistic can predict longer-term survival – it does not mean you will only survive for five years. Thyroid cancer has the highest five-year survival rate of all cancers (96%).

Women diagnosed with thyroid cancer generally have a slightly better prognosis than men (98% five-year survival rate).

"Sometimes I felt people were a little dismissive because thyroid cancer has a good outlook. They would say, ‘If you’re going to get cancer, that’s the best type to get.’ But I didn’t find this very helpful. Hearing the word ‘cancer’ made me feel gutted and afraid."

Which health professionals will I see? 

Your GP will arrange the first tests to assess your symptoms. This can be a worrying and tiring time, especially if you need several tests. If these tests do not rule out cancer, you will usually be referred to an endocrinologist or endocrine surgeon who will arrange further tests and advise you about treatment options.

You will be cared for by a range of health professionals who specialise in different aspects of your treatment. This multidisciplinary team (MDT) will depend on the stage of the cancer.

Health professionals for early thyroid cancer
endocrinologist specialises in diagnosing and treating disorders of the endocrine system
endocrine surgeon
operates on the thyroid gland, parathyroid glands, adrenal glands and the endocrine pancreas
ENT surgeon
treats the ears, nose and throat, including lymph nodes in the neck, and checks the vocal cords before and after surgery
head and neck surgeon
operates on cancer in the head and neck area
nuclear medicine specialist
coordinates the delivery of radioactive iodine treatment and nuclear scans
support patients and families throughout treatment and liaise with other staff


Additional health professionals you may see
medical oncologist prescribes and coordinates the course of chemotherapy
radiation oncologist
prescribes and coordinates the course of radiotherapy
other allied health professionals, e.g. counsellors, physiotherapists, dietitians and social workers
links you to support and rehabilitation services and helps with emotional, physical and practical issues

Key points 

  • Thyroid cancer often doesn’t cause any symptoms, but you may feel a painless lump in your neck or throat.
  • There are many different types of tests to diagnose thyroid cancer.
  • You may have a blood test to check the level of thyroid hormones in your blood.
  • Most people have an ultrasound and a fine needle biopsy to check for cancer in the thyroid tissue.
  • Other tests used to diagnose thyroid cancer include a CT scan, MRI scan or, occasionally, a PET scan.
  • A radioisotope scan is when radioactive fluid is injected into your body. Thyroid cells may not take up much fluid (‘cold’ nodules), or they may take up a lot of fluid (‘hot’ nodules). Knowing if the nodules are ‘cold’ or ‘hot’ may help detect cancer.
  • The doctor will tell you the size of the cancer and if it has spread (its stage). The TNM system is often used for staging. This stands for Tumour, Nodes, Metastasis.
  • Thyroid cancer has the highest five-year survival rate of all cancers (96%). Most thyroid cancers are treatable, and the cure rate is highest for papillary and follicular thyroid cancers.
  • You will see a doctor who specialises in treating disorders of the endocrine system. You may see other health professionals who work together as a multidisciplinary team (MDT) to diagnose and treat you. You will probably see more professionals if you have advanced thyroid cancer or need extra support.

Reviewed by: Dr Kiernan Hughes, Endocrinologist, San Clinic Specialist Rooms & Chatswood Rooms, Northern Endocrine Pty Ltd, NSW; Dr Daniel Badger, Medical Physicist, The Queen Elizabeth Hospital, SA; Dr Gabrielle Cehic, Nuclear Medicine Physician, Flinders Medical Centre, Lyell McEwin Hospital and The Queen Elizabeth Hospital, SA; Dr Ganessan Kichenadasse, Staff Specialist, Medical Oncologist, Flinders University School of Medicine, SA; Dr Christine Lai, Breast and Endocrine Surgeon, The Queen Elizabeth Hospital, SA; Jenny Lane, Consumer; Janny Wagenaar, Cancer Support Coordinator, Cancer Council TAS; and Cancer Council QLD Helpline Operators.
Updated: 01 Feb, 2014