Diagnosing thyroid cancer


If your doctor suspects you have thyroid cancer, they will feel your neck to check for any swelling or lumps. If you have a thyroid lump, your doctor may then perform one or more of the following tests to confirm whether the lump is cancerous. You may not have all of the tests described in this chapter, depending on your particular circumstances.

Blood test

You will have a blood test to check your levels of T3, T4 and thyroid-stimulating hormone (TSH). The thyroid gland generally functions normally even if thyroid cancer is present, and your hormone production won't be affected. However, this blood test may rule out benign thyroid conditions, such as hypothyroidism or hyperthyroidism.

If your doctor suspects you have medullary thyroid cancer, the levels of calcitonin in the blood may also be checked. High calcitonin levels in the blood can be a sign of this type of thyroid cancer.

Ultrasound

An ultrasound is the best way to get detailed information about your thyroid gland. The scan can show:

  • the size of any thyroid nodule and whether it is full of fluid or solid
  • whether a nodule has any characteristics that suggest it may be a thyroid cancer rather than a benign nodule
  • whether the lymph nodes in the neck appear to be affected.

The ultrasound 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. This creates a picture of the internal structure of your thyroid on a computer monitor. This test uses soundwaves and does not expose you to any radiation.

Biopsy

If you have a thyroid nodule or enlarged lymph node in your neck, you may need a fine needle aspiration (FNA) biopsy. This is an outpatient procedure that takes about 15–30 minutes.

During a FNA biopsy, a thin needle is inserted into the nodule to collect a sample of cells. You may be given local anaesthesia (pain relief) to numb the area, however, this is often not required. Ultrasound can also be used to guide the needle to the right spot. A pathologist will examine the sample under a microscope to see whether it contains cancer cells. If not enough cells are removed, the process may need to be repeated.

If it is not possible to determine whether a nodule is cancerous with a biopsy, it may be necessary to remove half of the thyroid ( hemithyroidectomy) to help confirm the diagnosis.

Biopsy results are usually available in around a week. This waiting period can be an anxious time and it may help to talk to a supportive friend, relative or health professional about how you are feeling. You can also call Cancer Council 13 11 20 for information and support.

Additional scans

The following scans are sometimes used to see if the cancer has spread from the thyroid gland to other parts of your body. This process is called staging. Some scans may be repeated after treatment to see how well the treatment has worked.

CT scan

A CT (computerised tomography) scan uses x-rays and a computer to create a detailed picture of an area inside the body.

In most cases, an ultrasound provides the information your doctor needs to make a diagnosis. However, you may need a CT scan if your thyroid is very enlarged, if it extends below the collar bones, or if your doctor suspects that the thyroid cancer has spread to other areas in the neck.

Before the scan, a special dye known as a contrast may be injected into one of your veins. This helps ensure that anything unusual can be seen more clearly on the pictures. The dye may make you feel flushed or hot, and it may produce a strange taste in your mouth for a few minutes.

The dye used in a CT scan can cause allergies in some people. If you know you're allergic to contrast or dyes, let the person performing the scan know in advance. You should also let them know if you are diabetic, have kidney disease or may be pregnant.

The CT scanner is a large, doughnut-shaped machine. You will lie on a table that moves in and out of the scanner. You will be asked to remain still and hold your breath for a few seconds during the scan. While it may take 30–60 minutes to prepare for the scan, the scan itself only takes a few minutes. Although a CT scan can be noisy, it is painless. You can go home once the scan is finished.

Let your health care team know if you feel uncomfortable or claustrophobic during the scan. You may be able to use headphones to listen to music, wear an eye mask or take a mild sedative.

PET scan

A PET (positron emission tomography) scan is rarely needed for thyroid cancer. However, it may be useful in some types of thyroid cancer, particularly if other tests give conflicting results.

To prepare for the PET scan, you will be asked not to eat or drink for a period of time (fast). Before the scan, you will be injected with a glucose solution containing a small amount of radioactive material. Cancer cells show up brighter on the scan because they take up more of the glucose solution than normal cells do.

You will be asked to sit quietly for 30–90 minutes while the glucose solution moves around your body. You will then have a scan of your entire body to locate any cancer cells. The scan itself takes about 30 minutes.

You should tell the doctor if you're diabetic, have kidney disease, are breastfeeding or if there is a possibility you may be pregnant.

Staging thyroid cancer

The tests described above help your doctors determine whether you have thyroid cancer and whether it has spread from the thyroid to other parts of the body. This testing process is called staging and it helps your health care team recommend the best treatment for you. It is often not possible to completely stage thyroid cancer until after surgery.

The TNM staging system is the method most commonly used to describe the different stages of thyroid cancer. Each letter is assigned a number to describe the cancer. Your age and cancer type will also help determine the stage of thyroid cancer.

Doctors use all this information to determine whether the cancer is low, intermediate or high risk.

If you are having trouble understanding staging, ask a member of your treating team to explain it in clearer terms.

TNM system

T (Tumour) 0–4

Indicates the size of the tumour. T1 cancers are smaller and remain inside the thyroid gland, while T4 tumours are larger or have spread to other parts of the neck.

N (Nodes) 0–1

Indicates whether the cancer has spread to the lymph nodes. N0 means the cancer has not spread to the lymph nodes; N1 means the cancer has spread to the nodes.

M (Metastasis) 0–1

Indicates if the cancer has spread to other parts of the body, such as the lungs or the bones (metastatic or secondary cancer). M0 means the cancer has not spread; M1 means the cancer has spread.

Prognosis

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 person 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 the same type of thyroid cancer as you.

To work out your prognosis, your doctor will consider:

  • your test results
  • the type of thyroid cancer you have
  • the size of the tumour and how quickly it is growing
  • how well you respond to treatment
  • other factors such as 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. See below for more information on survival rates.

Five-year survival rate

Doctors commonly use fiveyear survival rates as a way to discuss prognosis. This is because research studies often follow people for five years.

This statistic estimates the impact of the cancer on longer-term survival – it does not mean you will only survive for five years.

To determine the five-year survival rate, doctors collect information from people treated at least five years ago. Improvements in treatments may mean that your outlook is now better.

Thyroid cancer has a very high five-year survival rate (96%).3

Women diagnosed with thyroid cancer generally have a slightly better prognosis than men (97% five-year survival rate compared with 93%). Younger people also have a better prognosis than older people.

Which health professionals will I see?

Your GP will arrange the first tests to assess your symptoms. If these tests do not rule out cancer, you will usually be referred to an endocrinologist or endocrine surgeon. They will organise more tests and advise you about treatment options.

You will probably be cared for by a range of health professionals who specialise in different aspects of your treatment. This is called a multidisciplinary team (MDT). This team will meet regularly to discuss and plan the most appropriate treatment for you. See below for a list of some of the people who make up this MDT.

Health professionals for early thyroid cancer
 
endocrinologist* diagnoses, treats and manages disorders of the endocrine system
endocrine surgeon* operates on the thyroid gland, parathyroid glands, adrenal glands and the pancreas
ear, nose and throat (ENT) surgeon* operates on the ears, nose and throat, including the thyroid gland and lymph nodes in the neck; checks the vocal cords before and after surgery
head and neck surgeon* diagnoses and treats cancer of the head and neck; may be an ENT or general surgeon
nuclear medicine specialist* coordinates the delivery of radioactive iodine treatment and nuclear scans
nurses and nruse care coordinator administer drugs and provide care, support and information throughout treatment
 
Additional health professionals you may see
 
radiation oncologist prescribes and coordinates the course of radiotherapy
medical oncologist prescribes and coordinates drug therapies such as chemotherapy and targeted therapy
counsellor, social worker provide emotional and practical support; link you to support services
dietitian recommends an eating plan to follow during treatment and recovery

*Specialist doctor

Key points

  • Different types of tests are used to check for thyroid cancer, but the diagnosis is usually made by a fine needle aspiration (FNA) biopsy.
  • During a FNA biopsy a sample of cells is removed from a nodule for examination under a microscope. In some cases, an ultrasound is used to guide the needle to the right spot.
  • You will have a blood test to check the levels of thyroid hormones in your blood.
  • Treatment recommendations will depend on whether the cancer is assessed as low, intermediate or high risk.
  • Sometimes, the information needed for accurate staging is available only after surgery.
  • Your doctor will talk to you about your prognosis, which is the expected outcome of a disease. Thyroid cancer has a very high five-year survival rate (96%). Most thyroid cancers are treatable.
  • Occasionally other tests, such as a CT scan or a PET scan, are used to investigate if the thyroid cancer has spread.
  • 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.
  • You should 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 treat you.
  • You will probably see more professionals if you have advanced thyroid cancer or need extra support.

Expert content reviewers:

Dr Mark Pace, Endocrinologist, Royal Melbourne Hospital, VIC; Dr Roger Allison, Radiation Oncologist, Royal Brisbane and Women's Hospital, QLD; Dr Gabrielle Cehic, Nuclear Medicine Physician, Flinders Medical Centre and Queen Elizabeth Hospital, SA; Leisa Davey, Consumer; Ilona Lillington, A/Clinical Nurse Consultant Thyroid, Royal Brisbane and Women's Hospital, QLD; A/Prof Julie Miller, Specialist Endocrine Surgeon and Head of Thyroid/Endocrine Tumour Group, Royal Melbourne Hospital, VIC; Chris Sibthorpe, 13 11 20 Consultant, Cancer Council Queensland; Carly Smith, A/Clinical Nurse Consultant Thyroid, Royal Brisbane and Women's Hospital, QLD.

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