Thyroid cancer

Overview

Early thyroid cancer often causes no symptoms. A common sign is a painless lump in the neck that slowly gets bigger. The main types are papillary, follicular, medullary and anaplastic cancer. Surgery is the most common treatment, and radioactive iodine is usually offered afterwards. The outlook depends on the type and stage of the cancer, and a specialist team explains it for each person.

Symptoms

What a clinician may find

• A hard, painless lump in the front lower part of the neck that slowly gets bigger
• A hoarse voice that is not getting better
• Difficulty swallowing or breathing

Complications

• Spread to nearby lymph nodes in the neck, which may be removed during surgery
• Return of the cancer after treatment, which is one reason follow-up is arranged
• Low thyroid hormone levels after the thyroid is removed, which is why replacement tablets are usually needed

Diagnosis

A GP may examine the neck and arrange a blood test, and may refer the person urgently to a hospital specialist if cancer is a concern, which does not mean that cancer is certain. Blood tests mainly check thyroid function and cannot identify cancer on their own. An ultrasound scan of the neck helps estimate how likely a thyroid nodule is to be cancer and whether a biopsy is needed. A fine needle aspiration biopsy, in which a thin needle removes some cells from the lump, is the usual tissue test.

Treatment

Surgery to remove the thyroid is the most common treatment, and the surgeon may also remove nearby lymph nodes in the neck if the cancer has spread or might have spread. Radioactive iodine is usually offered after surgery to destroy any thyroid tissue left behind. After the whole thyroid is removed, hormone tablets are usually needed to replace the hormones it made. For more advanced disease, options include targeted medicines and radiotherapy.

Prevention

The causes of thyroid cancer are not known for most people, and having a risk factor does not mean that a person will develop it.

Key facts

What is thyroid cancer and what types are there?

Thyroid cancer starts in the thyroid gland, which sits in the front of the neck. The main types are papillary, follicular, medullary and anaplastic cancer. Papillary is the most common type, and follicular is less common. Papillary and follicular cancers are together called differentiated thyroid cancer. The National Cancer Institute describes both as generally slow growing, although rare aggressive forms exist.

Medullary thyroid cancer is rare and starts in the C cells of the thyroid, which make a hormone called calcitonin. Anaplastic thyroid cancer is very rare and fast growing, and the National Cancer Institute calls it the most aggressive type. The type affects treatment, because radioactive iodine is used mainly for differentiated cancers and is not used for medullary thyroid cancer. Macmillan Cancer Support has separate information pages on papillary and follicular, medullary and anaplastic thyroid cancer. Care is usually planned by a multidisciplinary team, which can include specialist surgeons, oncologists, cancer nurse specialists, radiologists and histopathologists who meet to discuss the best treatment.

What are the symptoms of thyroid cancer?

Early thyroid cancer often causes no symptoms, and it is sometimes found by chance on scans done for other reasons. The typical lump is in the front, lower part of the neck, and it usually feels hard, slowly gets bigger and is not painful. Other symptoms can include a hoarse voice, difficulty swallowing or breathing, and pain or pressure at the front of the neck.

Neck lumps are common and are usually caused by a less serious condition, such as an enlarged thyroid called a goitre. Thyroid cancer is uncommon, and most neck lumps turn out to be benign, which means not cancer. The NHS advises booking a GP appointment for a lump in the neck, a hoarse voice that is not getting better, or difficulty swallowing that is not getting better. If the GP is concerned about cancer, the person may be referred urgently to a hospital specialist, which does not mean that cancer is certain. NHS advice on goitre is to call 999 or go to A&E if a person finds it hard to breathe or has a wheezing noise when breathing.

What causes thyroid cancer and who is at risk?

Doctors do not know the exact cause of thyroid cancer in most people, but some risk factors can raise the chance of developing it. Having one or more risk factors does not mean that a person will get thyroid cancer. Radiotherapy to the head or neck, usually given in childhood, can increase the risk of thyroid cancer many years later, according to Cancer Research UK. A review of radiation-related thyroid cancer describes the thyroid as highly sensitive to radiation during childhood and adolescence.

Having a close relative with thyroid cancer raises the risk, and the risk is higher with more than one affected relative or a diagnosis at a young age. A long-standing goitre is listed as a risk factor, and Macmillan says some non-cancerous thyroid conditions, such as goitres and nodules, can slightly increase the risk. Macmillan also says that having an overactive or underactive thyroid does not increase the risk of thyroid cancer. Thyroid cancer is diagnosed more often in women than in men. For medullary thyroid cancer, NHS genomics education material says that genetic testing for the RET gene is offered to people diagnosed, and that relatives can be offered testing if a gene change is found.

How is thyroid cancer diagnosed?

A GP may examine the neck and arrange a blood test. Blood tests mainly check how the thyroid is working, and Macmillan notes that cancer cannot be identified from a blood test alone. The GP may refer the person to a hospital specialist for further tests.

An ultrasound scan of the neck is usually the first imaging test once a lump or nodule has been found. Features seen on ultrasound, such as the size and edges of the nodule, help estimate how likely it is to be cancer and whether a biopsy is needed. Fine needle aspiration is the usual tissue test and is often guided by ultrasound. In this test a thin needle removes some cells from the lump so that they can be examined under a microscope. If the result is unclear, a core needle biopsy or a surgical biopsy may follow. The National Cancer Institute describes thyroglobulin and calcitonin blood tests as supporting markers, and advises that biopsy samples can be reviewed by a pathologist with experience of thyroid cancer.

How is thyroid cancer treated?

Surgery is the most common treatment for thyroid cancer, according to the NHS. The operation removes the thyroid, which is called a thyroidectomy, and the surgeon may also remove some lymph nodes in the neck if the cancer has spread or might have spread to them. Radioactive iodine is usually offered after surgery, and its purpose is to destroy any thyroid tissue left over. It is usually given as a capsule or tablet, and treatment can involve a short stay in hospital.

The thyroid and most differentiated thyroid cancer cells take up iodine, so the radiation acts on them directly. Radioactive iodine is not used to treat medullary thyroid cancer. After the whole thyroid is removed, hormone tablets are usually needed to replace the hormones it made, and some hospitals note that the tablets can also help stop the cancer coming back. For more advanced disease, the National Cancer Institute lists targeted therapy and external radiotherapy as options, and chemotherapy is often combined with radiotherapy in anaplastic thyroid cancer. The multidisciplinary team discusses the best treatment, including the extent of surgery, and then talks it through with the patient.

What happens after treatment and what is the outlook?

After treatment, follow-up checks look for any remaining or returning cancer. Neck ultrasound and blood tests, including thyroglobulin, are the main follow-up tools in differentiated thyroid cancer. Macmillan explains that thyroglobulin is normally absent once the thyroid is removed and radioactive iodine given, so a detectable level can suggest remaining cancer cells. For medullary thyroid cancer, Cancer Research UK lists calcitonin as the tumour marker, and levels can rise for reasons other than cancer.

How often follow-up is needed varies with the risk of the cancer coming back, and one patient guide says that people with low-risk cancers removed by surgery may not need follow-up care. Replacement hormone tablets, usually levothyroxine, are typically needed for life after the thyroid is removed. The outlook depends on the type and stage of the thyroid cancer, and the specialist team can explain what this means for each person.

Frequently asked questions