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Thymus gland tumours

Find out about the thymus gland, thymoma and thymic carcinoma. 

The thymus is a gland in the chest. It's at its largest in adolescence and then gradually shrinks away throughout adulthood, being replaced with fatty tissue. It is involved in the development of white blood cells called T lymphocytes.

Diagram showing the position of the thymus

Cancer of the thymus is not common. Most tumours in the thymus are called thymomas. There is also a much rarer form of thymus gland cancer called thymic carcinoma.

Most thymus tumours are in the front of the chest but more rarely, they develop in the neck.

Thymoma

Thymomas are generally slow growing tumours found most often in people between the ages of 40 and 60.

The tumours vary in how they behave. Some grow very slowly. Others grow more quickly 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 the body.

Like many other cancers, we don't know exactly what causes thymomas. About 4 out of 10 people diagnosed (40%) have another condition called myasthenia gravis. Myasthenia gravis 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.

Symptoms

Many people don't have any symptoms from their thymoma. They can be found by accident, when you're having a chest x-ray for something else. If you do have symptoms, they might include difficulty swallowing, a cough and tiredness.

Treatment 

The main treatment for thymoma 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.

Other thymomas don't have the fibrous capsule and are more difficult to remove completely. If your thymoma can't be completely removed, or if there is a risk that it will come back, you might have a course of radiotherapy after surgery.

Most people with thymoma are cured with either surgery alone or surgery followed by radiotherapy.

Thymoma that comes back

If the cancer does come back you might have chemotherapy. There is no standard treatment because this is a rare condition. But chemotherapy often includes a drug called cisplatin. Unfortunately, if your thymoma does come back, it isn't usually possible 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 tumour responds to treatment.

Thymic carcinoma

Thymic carcinoma is much rarer than thymoma. It tends to grow more quickly and is more likely to spread to other parts of the body. Thymic carcinomas are found in all age groups but are most common in middle aged and older adults.

Symptoms

Most people have symptoms. These include a cough, shortness of breath and chest pain. It is much rarer to also have an autoimmune condition such as myasthenia gravis with thymic carcinoma than it is with thymoma.

Treatment

Most people have treatment with surgery and either radiotherapy or chemotherapy, or both. The most common type of treatment is surgery followed by radiotherapy. The surgeon will take out as much of the tumour as possible. They then use radiotherapy to try and kill off any cancer cells left behind.

Unfortunately, thymic carcinoma is harder to cure than thymoma. This is because it often spreads quite early on. The cancer can spread to the lungs and lymph nodes in the chest. In some cases, it may also spread to the bones or to the liver.

Survival statistics

It's difficult to find reliable statistics for the outlook of conditions as rare as thymic carcinoma. But around a third of the people diagnosed with thymic carcinoma are likely to live for at least 5 years.

Coping

Coping with a diagnosis of a rare 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

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.

Last reviewed: 
19 Feb 2015
  • Principles and practice of oncology (10th edition)

    VT DeVita and others, 2011

  • Textbook of Uncommon Cancer (4th Edition)

    D Raghavan and others

    Wiley Blackwell, 2012

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