Medullary thyroid cancer
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Medullary thyroid cancer (MTC) is a rare type of thyroid cancer. About 5 to 10 out of 100 (5 to 10%) of thyroid cancers are MTC.
It is often slow-growing. It starts in cells in the thyroid gland called parafollicular cells, or C cells. These cells normally make a hormone called calcitonin, which helps control the level of calcium in the blood.
The most common symptom of medullary thyroid cancer (MTC) is a mass or lump in the neck, which may be painful.
Other symptoms may include:
- difficulty swallowing – caused by the thyroid tumour pressing on the gullet (oesophagus)
- difficulty breathing – caused by the thyroid tumour pressing on the windpipe (trachea)
- a hoarse voice that has no obvious cause and does not go away after a few weeks
- a feeling of pressure or discomfort in the neck.
Less common symptoms include:
- a red face (flushing)
- having softer stools (poo) or diarrhoea often
- weight loss.
These can be caused by the tumour making too much of the hormone calcitonin.
For most people, the cause of medullary thyroid cancer (MTC) is unknown. This is called sporadic medullary thyroid cancer.
About 1 in 4 people (25%) who develop MTC have a rare inherited genetic condition called multiple endocrine neoplasia type 2 (MEN2).
There are 3 types of MEN2:
- MEN2B (also called MEN3)
- familial medullary thyroid cancer (FMTC).
These are rare conditions. MEN2A and MEN2B can also cause growths (tumours) in other endocrine glands.
Almost everyone with MEN2 will develop MTC. Children and young adults with the MEN2 gene usually have an operation to remove the thyroid gland. This is to prevent cancer developing.
If you are diagnosed with MTC, you may have a blood test to look for gene changes. If the test shows changes, your doctor will refer you to a specialist genetics service. The specialist will give you more information about the gene changes. They will also discuss whether any members of your family may also need to be tested.
You usually start by seeing your GP, who will examine you. They will refer you to a hospital for specialist advice and treatment if they:
- are unsure what the problem is
- think your symptoms could be caused by cancer.
If they think it could be cancer, you should be seen at the hospital within 2 weeks.
At the hospital, the doctor will ask you about your general health, any previous medical problems and your family history. They will also examine you. You may have some of the following tests:
An ultrasound scan uses sound waves to build up a picture of the inside of the neck and the thyroid gland. Your doctor will also check the lymph nodes in your neck to see if any of them are abnormal. This is because thyroid cancer can sometimes spread to the lymph nodes. The scan only takes around 10 to 15 minutes and is painless.
Fine needle aspiration (FNA)
A doctor gently passes a small needle into the lump or swelling in your neck. Sometimes the doctor uses an ultrasound scan to help guide the needle to the right area. Then they take a small sample of cells and examine it under a microscope to check for any abnormal cells.
If an FNA does not collect enough cells, it may need to be done again.
If the tests show you that have thyroid cancer, your doctor may want to do some further tests. These are to find out the size and position of the cancer, and whether it has spread to other parts of the body. This is called staging. Knowing the stage of the cancer helps you and your doctor decide on the best treatment for you.
These tests may include the following:
These check for the levels of calcitonin and calcium in your blood. You may also have a blood test to check the levels of a protein called CEA in the blood. CEA is a tumour marker. It can help your doctor monitor how well treatment is working.
24-hour urine sample
Some people who have MEN2 may have non-cancerous growths, called phaeochromocytomas on the adrenal glands. This test checks if the adrenal glands are affected. It is done even if there is no family history of MEN2.
Vocal cord check
The treatment you have for medullary thyroid cancer (MTC) depends on the stage of the cancer and your general health. A team of specialists meet to talk about the best treatment for you. They are called a multidisciplinary team (MDT).
Treatments may include:
Surgery is the main treatment for MTC. A surgeon usually removes the whole thyroid gland (total thyroidectomy). They may also take out some lymph nodes. How much surgery you need depends on the results of your scans and blood tests (your calcitonin level).
If your thyroid gland has been removed, you will need to take thyroid hormone tablets (levothyroxine) every day for the rest of your life. These replace the thyroid hormones your body needs to function at its normal rate.
External beam radiotherapy
Other treatments include:
Radiolabelled therapies uses a radioactive substance, which is attached to a type of chemical, to destroy the cancer. Some MTCs absorb large amounts of certain chemicals. This treatment is not often used. It is more common to have targeted therapies.
Clinical trials (research trials) try to find new and better treatments for cancer. Because MTC is rare, it is more difficult to research new treatments. Ask your thyroid specialist if there are any clinical trials suitable for you.
Even if it has spread, MTC usually grows very slowly. It often does not cause any symptoms for many years. Your doctor might recommend follow-up appointments with blood tests and scans. If they find changes, for example a rise in calcitonin, your doctors may plan more treatment.
Some people have treatment side effects that slowly improve over time, while others may have ongoing side effects. It can take time to recover after treatment for thyroid cancer.
You will have regular follow up appointments after your treatment has finished. If you have any problems or notice any symptoms between check-ups, tell your doctor as soon as possible.
You may have lots of different emotions after being diagnosed with cancer. You may get anxious between appointments. This is natural. It may help to get support from family, friends or a support organisation.
Macmillan is also here to support you. If you would like to talk, you can:
Other useful organisations
There are also other organisations that can give you information and support. These include:
Below is a sample of the sources used in our thyroid cancer information. If you would like more information about the sources we use, please contact us at firstname.lastname@example.org
British Medical Journal. Best Practice Guidelines, Thyroid cancer. 2020.
European Society Medical Oncology (ESMO): Thyroid cancer, Clinical Practice Guidelines for Diagnosis, Treatment and Follow-up. 2019.
National Institute for Health and Care Excellence (NICE). TA535: Lenvatinib and Sorafenib for treating differentiated thyroid cancer after radioactive iodine. 2018. www.nice.org.uk/guidance/ta535 [accessed May 2021].
This information has been written, revised and edited by Macmillan Cancer Support’s Cancer Information Development team. It has been reviewed by expert medical and health professionals and people living with cancer. It has been approved by Senior Medical Editor, Professor Nick Reed, Consultant Clinical Oncologist.
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