Your guide to Medullary Thyroid Cancer

Content overview

What is medullary thyroid cancer?

How common is it?

Is there a genetic link?

How is it diagnosed?

How is it treated?

How is it followed up?

Long term follow up

Further information

What is medullary thyroid cancer? 

Medullary thyroid cancer (MTC) is a rare type of thyroid cancer which originates in the parafollicular C cells in the thyroid.  It is different from other, more commonly diagnosed forms of thyroid cancer (follicular and papillary) which start in the follicular cells of the thyroid.

The C cells produce a hormone called calcitonin which can be used as a tumour marker for the MTC. Parafollicular cells are neuroendocrine cells and as a result the cancer travels and acts differently to other forms of thyroid cancer.

How common is it?

MTC is rare and affects 1 in 400,000 of the population. It accounts for 5% of all thyroid cancers.

Is there a genetic link?  

In up to 1 in 4, or 25%, of all MTC cases a genetic link will be found which means that it can be passed down in families.

All patients with MTC should be offered genetic testing. The main gene tested is the RET oncogene. This is linked with Multiple Endocrine Neoplasia Type 2 (MEN2) disorders. If blood is sent off for genetic testing, it can take some time for the results to come back, and this will often be after your treatment has started.

Because of the time it takes to get results of genetic testing, if you are diagnosed with MTC before your treatment is started, extra blood and sometimes urine tests are usually taken before surgery. This will measure levels of parathyroid hormone, calcium levels and plasma or urine metanephrines or catecholamines to see if your adrenal and parathyroid glands are affected.  This is crucial information to help guide the surgeon and the anaesthetist before your thyroid surgery.

In addition to being offered genetic testing you should also be referred to a genetic counselling service at which you can discuss the risks to your children and other family members.

Find dedicated patient information about MEN syndromes from AMEND

How is it diagnosed?

Medullary thyroid cancer can present in many ways but usually as a thyroid lump or an enlarged lymph node.  Sometimes MTC may cause diarrhoea and the link with a problem in the neck is not clear.

The diagnosis may be confirmed with an ultrasound and a fine needle aspiration (FNA) or biopsy of the lump or lymph node. The MTC cells look different from the usual thyroid follicular cells in the FNA sample when evaluated under a microscope. Additional blood tests, including calcitonin and CEA (carcinoembryonic antigen) may also  help the medical team diagnose this condition.

Some people need further imaging of the neck (CT scan or MRI scan) ahead of surgery.  The chest and abdomen may also be imaged to check that the disease has not spread outside the neck.

How is it treated?

Usually, the first line treatment for MTC is surgery which removes the whole thyroid gland (total thyroidectomy) as well as dissection (or removal) of the lymph nodes in the neck. The extent of the dissection of lymph nodes in the neck will depend on how far the disease has spread. This will be determined by the results of the scans, blood tests and the biopsy, all of which are discussed at a regional thyroid cancer multidisciplinary team meeting.

There are national guidelines that help guide this surgery. It should be carried out by an experienced surgeon who regularly undertakes MTC surgery and usually takes place in a large thyroid cancer centre.

Your surgeon should explain to you the reasons for the extent of the surgery needed in your case and also about the possible complications of surgery. Usually, the MTC tumour will be removed by surgery. However if it is not possible to remove the whole tumour, radiotherapy or drug  treatment  may be available as an option.  

If the tumour is very advanced, e.g. it has spread to the windpipe or other structures in the neck, targeted therapies (e.g. Vandetanib, Cabozantinib, Selpercatinib) may be given to try and shrink the tumour before considering surgery.  Extra testing (such as molecular profiling) can be used to guide further treatment. These treatments are usually given by oncologists. 

How is it followed up?

After the surgery, the medical team will understand more about the disease and how far it has spread, by looking carefully at the surgical specimen under the microscope. They will decide a plan for the follow up care needed and discuss this with you. This will include details about medications you need to take, follow-up blood tests (CEA and calcitonin) and how often they should be taken.

Levothyroxine is used to replace the thyroid hormone your body can no longer make after thyroidectomy and you will need to take it for the rest of your life. It can sometimes take several months to find the right dose for you, but blood tests will guide the amount you need.

Patients with MTC are usually followed up life-long with clinical neck examination, blood tests (to measure calcitonin and CEA) and ultrasound imaging. Depending on the calcitonin and CEA results you may need further imaging with CT, MRI or PET scans.

Long term follow up

Sometimes the levels of calcitonin and CEA can be elevated after the operation and other treatments, even though there is no evidence of recurrence of any MTC on imaging tests. If this happens calcitonin and CEA will continue to be monitored, but unless they are increasing rapidly, no further imaging may be carried out at that time.

Neuroendocrine tumours can often live quietly in the body without causing problems, sometimes for many years.

Further information

MTC - AMEND
BTF Guide to Thyroid Surgery

March 2026