What is thyroid cancer?

Lumps (nodules) can sometimes appear on the thyroid gland, a butterfly shaped gland in front of the neck. These are made of an overgrowth of cells and are usually benign non-cancerous. However, sometimes the lump is made up of cells that continue to grow in an unrestricted way that may eventually invade structures next to the thyroid or spread to other parts of the body. These are known as cancerous cells and thyroid cancer refers to this cancerous growth originating within the thyroid gland.

What causes thyroid cancer?

In most patients the reason for the cancer starting is never discovered, however there are known risk factors.

• Pre-existing thyroid condition - it is a little more common in patients who have a pre-existing thyroid condition such as a multinodular goitre or Hashimoto's thyroiditis, but most thyroid cancers appear as a single nodule in the thyroid.
• High dose radiation - if the thyroid has been exposed to high dose radiation in the past, this increases the risk of benign nodules as well as thyroid cancer. High risk groups include people who have received radiotherapy or are survivors of atomic explosions or accidents. Some specialists recommend that patients who have had radiotherapy to the neck as a treatment for cancer - should have regular thyroid checks. The small doses of radiation in normal X-rays of the neck or in radioactive iodine used to treat an overactive thyroid do not seem to lead to an increased risk of cancer.
• Age - older age is a risk factor for thyroid cancer.
• Obesity - thyroid cancer cases caused by overweight and obesity in UK was estimated to be 8% in 2015.
• Family history and genetic factors in a very small number of families, more cancers are found than would normally be expected by chance. In some cases an abnormal gene can be found as in papillary cancer and medullary cancer of the thyroid.

Types of thyroid cancer?

• Papillary cancer – the most common type of thyroid cancer, slow-growing, common in younger people and has an excellent outlook.
• Follicular cancer - second most common type, usually in older people, slow-growing and may spread to other areas. The prognosis is good but Hürthle cell cancer is a type of follicular cancer which is rare and aggressive.
• Medullary cancer - rare cancer that may occur spontaneously or may be inherited
  Anaplastic cancer – extremely rare cancer that is unfortunately very aggressive and maybe difficult to treat.
• Lymphoma - rarely lymphoma may occur in the thyroid gland

What are the signs and symptoms of thyroid cancer?

Lump in the neck: Most patients with thyroid cancer will first visit their doctor when they discover a lump in the neck. Normal thyroid gland cannot be felt. If a GP thinks that the lump might be a thyroid cancer, an urgent appointment at a specialist clinic is made available within two weeks under the NHS rules. How long the lump has been present is not a very good guide to whether or not it is cancer. Usually the lumps are painless. Patients may also present with pain in the neck. If the cancer spreads to nearby lymph nodes, these may be felt as well.

Thankfully, most patients with these symptoms turn out not to have thyroid cancer, but they all need to be investigated.

Other symptoms due to pressure on the surrounding structures include:

- Changes in the voice such as hoarseness
- Difficulty swallowing
- Difficulty breathing

Sometimes thyroid cancer is detected by chance when a patient has a scan for an unrelated reason.

How common is thyroid cancer?

Thyroid cancer itself is rare in the UK and accounts for 1% of all new cancer cases in UK (2017).
According to research, around 3500 patients in the UK were newly diagnosed with thyroid cancer in 2015-2017 and compared to the previous decade, the incidence rates of thyroid cancer have increased by more than two-thirds (68%) in the UK.

Incidence rates for thyroid cancer in the UK are highest in people aged 65 to 69 (2015-2017).
Women are two to three times more likely than men to be affected. The quoted lifetime risk for women of developing thyroid cancer is one in 170 and for men one in 332.

How is thyroid cancer diagnosed?

The doctor will examine the patient and take blood tests to assess how well the thyroid is functioning. Most tests are carried out as an outpatient.

• Blood tests - thyroid cancer can happen with a normal or underactive thyroid and sometimes with an overactive thyroid. Blood tests are not used to diagnose thyroid cancer.
• Imaging - the patient may have an ultrasound scan to look at the thyroid and the adjacent lymph nodes and, if required, will have some form of needle test. Thyroid nodules are very common and less than 1 in 10 will be a thyroid cancer. For a thyroid scan, a person gets a pill or liquid with a small amount of a radioactive substance, then a special camera takes a picture of the thyroid.
• Fine needle aspiration - most doctors use a small needle (the same as for blood tests) to remove some thyroid cells from the gland that are then examined under a microscope. The test might sound frightening but, in fact, usually hurts even less than a simple blood test. The result can take a few days to be returned and usually clinches the diagnosis.

If the doctor cannot confidently rule out thyroid cancer, the test might need to be repeated. Sometimes the only way to be certain whether a thyroid lump is cancerous is to remove the part of the thyroid which contains the lump for examination. This is called a biopsy.

If a conclusion still cannot be made, the side of the thyroid containing the suspicious lump can be removed under general anaesthetic (thyroidectomy). Before this, most patients also have a check-up to make sure that the nerves to the voice box are working normally.

To assess the spread of the cancer other imaging tests are used.

How is thyroid cancer treated?

Thyroid cancer generally has a very good outlook. The treatment will be planned taking into account which type of thyroid cancer the patient has, how far the cancer has spread, the patient’s age, general health and level of fitness. The main treatment options that may be considered include surgery and radioactive iodine therapy. A multidisciplinary team (MDT) consisting of doctors and other professionals will discuss the best treatment care plan.

• Surgery - the mainstay of treatment is surgery. Depending on the type and size of the cancer, part or whole of the thyroid is be removed. Along with the thyroid, the affected lymph nodes nearby will be removed.
• Radioactive iodine – often recommended after surgery, a small amount of radiation is provide via a pill or liquid to destroy rest of the thyroid gland. Treatment with radioactive iodine requires a few days’ stay in hospital and there are usually some restrictions on how much time the patient can spend near other people, particularly children, for a period of time after they leave the hospital.
• Thyroid hormone therapy - after surgery or radioactive iodine therapy sufficient doses of thyroid medication thyroxine to keep a hormone called thyroid stimulating hormone at desired levels in the blood.
• External radiotherapy – direct beams of radiation are targeted to destroy cancer cells
  Chemotherapy - medicines to kill or halt growth of cancer cells can be used.
• Observation - when the cancer is very small and depending on other factors, a wait and watch approach may be taken.
• Targeted therapies - these newer medications attack specific targets on cancer cells

Are there any side-effects to the main treatment modalities?

All surgery carries some risks but, although serious complications from thyroid surgery are rare, it is important that the patient has them explained in detail by the surgeon.

Changes in the quality of the voice are usually very small, temporary and only a problem for people who use their voice professionally. More significant voice change, which makes the voice very weak, usually recovers over time.

Surgery may result in damage to the parathyroid glands, which are 4 small pea sized glands in the neck just next to the thyroid. As a result the blood calcium levels may be low causing a tingling sensation in your hands, feet or around the mouth. If they have any concerns, they should ask their doctor.

Radioactive iodine therapy does not affect the ability to have children in men or women, but a delay is necessary after the treatment before starting to try for pregnancy. Women should avoid getting pregnant for at least 6 months and men should avoid fathering a child for at least 4 months. It may result in neck pain, swelling, feeling sick, dryness or unpleasant taste in the mouth. It does not make hair fall out or affect body weight.

What are the longer-term implications of thyroid cancer?

The majority of patients with thyroid cancer can be treated successfully, but it can be fatal. Following successful treatment, patients usually have a blood test every year, and in some cases, regular scans are recommended. This is to monitor for recurrence. Around 9 in 10 (91.4%) of people diagnosed with thyroid cancer in England survive their disease for one year or more (2013-2017) and 84% survive their disease for ten years or more (2013-2017).

Most patients will be taking thyroxine tablets for life. Unless there have been any complications from surgery, patients usually return to all their previous activities.

Are there patient support groups for people with thyroid cancer?

British Thyroid Foundation or Butterfly Thyroid Cancer Trust may be able to provide advice and support to patients and their families dealing with thyroid cancer.