Cancer of the thymus is rare. Most cancers in the thymus are called thymomas. There’s also a much rarer form of thymus gland cancer called thymic carcinoma.

The thymus gland

The thymus gland is in your chest, in between your lungs.

A gland is an organ in your body which makes and releases a substance such as hormones.

The thymus gland is involved in the development of white blood cells called T lymphocytes. These white blood cells are part of your immune system and fight infection.

90 out of 100 (90%) thymus tumours are in the front of the chest but rarely they might develop in the neck.

Thymomas and thymic carcinomas are most common in people between the ages of 50 and 60. But children and elderly people can also get these tumours.

Types of thymus gland tumours

Thymomas and thymic carcinomas are cancers of the cells that line of the thymus gland (epithelial cells). 

Thymoma

Thymoma’s can vary in how they behave. Some grow very slowly. Others grow faster and can spread to the lungs or the covering of the lungs (the pleura). It's very unusual for them to spread anywhere else in your body.

Like many other cancers, we don't know exactly what causes thymomas.

Some people with thymomas also have a condition affecting their immune system.

Around 30 out of 100 people diagnosed with thymoma’s (30%) have another condition called myasthenia gravis (MG). MG is an autoimmune disease. Thymoma has been linked to other autoimmune diseases, such as:

• systemic lupus erythematosus (SLE)
• rheumatoid arthritis

Thymoma has also been linked to blood conditions such as pernicious anaemia, hypogammaglobulinemia, and red cell aplasia.

Thymic carcinoma

Thymic carcinomas are much rarer than thymoma’s. They tend to grow more quickly and are more likely to spread to other parts of your body. Because of this they are usually harder to cure.

It’s much rarer to also have autoimmune conditions with thymic carcinoma than it is with thymoma. 

Symptoms of thymus gland tumours

Symptoms might include:

• chest pain
• a cough that won’t go
• shortness of breath
• difficulty swallowing
• hoarseness of the voice
• loss of appetite

The thymus is close to the superior vena cava. This vein carries blood to the heart. The cancer can press on it and cause superior vena cava syndrome. Symptoms can include:

• swelling in the face, chest and upper neck
• headaches
• feeling dizzy or lightheaded

Sometimes thymus gland tumours don’t cause any symptoms. They can be found by accident, when you're having a chest x-ray, CT of the chest or a CT angiogram for something else.

Tests you might have

Your doctor will arrange for you to have tests. These include:

• chest x-ray
• CT scan
• PET scan

The doctor might take a sample (biopsy) of your cancer before your operation. You might not need to have a biopsy if your doctor thinks it’s very likely that you have a thymic tumour

Treatment

The most common treatments for thymoma are:

• surgery
• radiotherapy
• chemotherapy

You might have one or more of these treatments. Most people with operable thymoma are cured with either surgery alone or surgery followed by radiotherapy.

Surgery

The main treatment for thymus gland cancer is an operation to remove it.

Many thymomas are covered in a fibrous sheet called a capsule. These thymomas are often quite easy to remove and are usually cured with surgery alone.

The most common surgery for thymus gland tumours is the complete removal of the thymus gland (thymectomy) and the cancer. The surgeon often makes a cut down the middle of the chest, to remove the thymus and cancer. This is called a sternotomy.

Sometimes you might have keyhole surgery instead. Keyhole surgery involves your surgeon making small incisions (cuts) rather than large ones, they then carry the surgery out through these excisions.

Radiotherapy

Radiotherapy means the use of radiation, usually x-rays, to treat cancer cells.

You might have radiotherapy after surgery (post operative radiotherapy) if:

• your surgeon thinks they haven’t been able to remove all the cancer
• there is a high risk that your thymoma will come back

The surgeon removes as much of the cancer as possible. They then use radiotherapy to try and kill off any cancer cells left behind.

You might have radiotherapy as your main treatment if you can’t have surgery.

Chemotherapy

Chemotherapy uses anti cancer (cytotoxic) drugs to destroy cancer cells.

You might have chemotherapy:

• to try and shrink the cancer so that surgery is possible (neoadjuvant chemotherapy)
• if your cancer comes back

The chemotherapy drugs you might have include cisplatin, carboplatin, doxorubicin etoposide, paclitaxel, and cyclophosphamide.

If you have thymic carcinoma, you might have post operative chemotherapy (chemotherapy after surgery). Your doctor decides whether you need this, based on whether your surgeon can remove all the tumour.

Unfortunately, if your thymus gland tumour does come back, it can be difficult to get rid of it altogether. But treatment can often keep it under control for some time.

Your doctor will be able to tell you more, by keeping a close eye on how your cancer responds to treatment.

Coping

Coping with a diagnosis of a more aggressive cancer can be especially difficult, both practically and emotionally. Being well informed about your cancer and its treatment can make it easier to make decisions and cope with what happens.

Talking to other people who have the same thing can also help.

Our discussion forum Cancer Chat is a place for anyone affected by cancer. You can share experiences, stories and information with other people who know what you are going through.

The Rare Cancer Alliance offer support and information to people affected by rare cancers.