Thymus gland cancer is rare and the cause is not known. However, other types of cancer can affect the thymus gland, such as lymphomas, germ cell tumours and neuroendocrine tumours. These are treated in different ways.

The thymus gland sits in the chest, behind the breastbone and between the lungs. The thymus makes white blood cells called T lymphocytes. These are part of the body's immune system and help fight infection.

The thymus gland does most of this work when you’re a child and teenager. It then gradually becomes less active, shrinks and is replaced by fat and scar tissue.

Some people with thymus gland cancer also have an immune system condition (autoimmune disorder). The immune system is the way your body protects itself from infection and disease. Sometimes this system doesn’t work properly, and starts fighting normal, healthy cells in the body instead of just fighting infection and disease.

Myasthenia gravis

The most common condition linked to thymus gland cancer is called myasthenia gravis. The main symptom of this is that the muscles become tired and weak. About half of the people with a thymoma also have myasthenia gravis.

Hypoglobulinaemia

Another condition linked to thymus gland cancer is hypoglobulinaemia. People with hypoglobulinaemia have very low levels of antibodies in the blood. Your immune system makes antibodies to find and destroy infections. If you don’t have enough antibodies, you are more likely to catch infections, and take longer to recover from them. Between 5–10% of people with a thymoma also have hypoglobulinaemia.

Pure red cell aplasia

About 1 out of every 20 people (5%) who have a thymoma have a condition called pure red cell aplasia. This disorder stops the body making enough red blood cells. Red blood cells carry oxygen around the body. If you don’t have enough of them, you can become tired and sometimes breathless.

If you have a condition linked to thymus gland cancer, your doctor or specialist nurse can tell you more about managing any symptoms you may have.

Symptoms may include:

• chest pain
• a persistent cough or coughing up blood
• becoming breathless or wheezy
• difficulty swallowing
• a hoarse voice.

Sometimes thymus gland cancer doesn’t cause any symptoms and is found during tests for something else. You may also have tests for thymus gland cancer if you have a condition such as myasthenia gravis (see above).

If you have symptoms, you usually start by seeing your GP. If they are unsure what the problem is, or think your symptoms may be caused by cancer, they will refer you to a hospital specialist.

The specialist doctor at the hospital will ask you about your symptoms and general health before examining you.

They may use the following tests to diagnose thymus gland cancer:

Chest x-ray

X-rays use high-energy rays to take a picture of the inside of your body. Your doctor can use an x-ray of your chest to look at your thymus gland.

CT (computerised tomography) scan

A CT scan takes a series of x-rays, which build up a three-dimensional picture of the inside of the body. The scan takes 10–30 minutes and is painless. It uses a small amount of radiation, which is very unlikely to harm you and will not harm anyone you come into contact with. You will be asked not to eat or drink for at least four hours before the scan.

You may be given a drink or injection of a dye, which allows particular areas to be seen more clearly. This may make you feel hot all over for a few minutes. It’s important to let your doctor know if you are allergic to iodine or have asthma, because you could have a more serious reaction to the injection.

You’ll probably be able to go home as soon as the scan is over.

PET-CT scan

This is a combination of a CT scan, which takes a series of x-rays to build up a three-dimensional picture, and a positron emission tomography (PET) scan. A PET scan uses low-dose radiation to measure the activity of cells in different parts of the body.

PET-CT scans give more detailed information about the part of the body being scanned. You may have to travel to a specialist centre to have one. You can't eat for six hours before the scan, although you may be able to drink.

A mildly radioactive substance is injected into a vein, usually in your arm. The radiation dose used is very small. The scan is done after at least an hour’s wait. It usually takes 30–90 minutes. You should be able to go home after the scan.

MRI scan

This test uses magnetism to build up a detailed picture of areas of your body. The scanner is a powerful magnet so you may be asked to complete and sign a checklist to make sure it's safe for you. The checklist asks about any metal implants you may have, such as a pacemaker, surgical clips, bone pins, etc. You should also tell your doctor if you've ever worked with metal or in the metal industry as very tiny fragments of metal can sometimes lodge in the body. If you do have any metal in your body it's likely that you won't be able to have an MRI scan. In this situation another type of scan can be used.

Before the scan, you'll be asked to remove any metal belongings including jewellery. Some people are given an injection of dye into a vein in the arm, which doesn't usually cause discomfort. This is called a contrast medium and can help the images from the scan to show up more clearly. During the test you'll lie very still on a couch inside a long cylinder (tube) for about 30 minutes. It's painless but can be slightly uncomfortable, and some people feel a bit claustrophobic. It's also noisy, but you'll be given earplugs or headphones. You can hear, and speak to, the person operating the scanner.

Doctors may be able to diagnose thymus gland cancer using the tests listed above. But sometimes they need to collect a sample of tissue or cells (biopsy) from your thymus gland. A doctor who specialises in analysing cells (pathologist) can then examine the tissue under a microscope for cancer cells. A biopsy can be taken in different ways:

CT-guided needle biopsy

The doctor numbs the skin on your chest with a local anaesthetic. Then they use a needle to collect cells from the thymus gland. During this test they use CT scans to guide the needle.

Mediastinoscopy

If the doctor can’t get a sample of cells using a needle biopsy, you may have this test under a general anaesthetic. The doctor makes a cut about two inches long on the front of the chest. They pass a thin tube with a light and camera on it through the cut. The tube helps the doctor see the thymus gland and take biopsies.

Thoracoscopy

Sometimes the doctor will use this test to take a biopsy. It is like a mediastinoscopy, but the doctor makes cuts on the side of the chest. This can be done using local anaesthetic and sedation or under a general anaesthetic.

At the end of the test, the doctor may put a drain into your chest. This is a flexible tube that lets any air or fluid drain out from your chest into a bottle. A nurse usually takes the chest drain out after 1–3 days. You need to stay in hospital until it’s taken out.

The stage of a tumour describes its size and whether it has spread. Knowing the stage helps doctors decide on the best treatment for you.

• Stage 1 The cancer is inside the thymus gland and has not spread.
• Stage 2 The cancer has spread through the outer lining of the thymus gland or into the fat around it.
• Stage 3 The cancer has spread into nearby organs such as the lungs or the lining of the heart (pericardium). It may have also grown into the blood vessels near the heart.
• Stage 4A The cancer has spread widely into the lining of the lungs (pleura) and the lining of the heart (pericardium).
• Stage 4B The cancer has spread to other distant organs, such as the liver.

The doctor examines the cancer cells under a microscope to work out the grade and type of the cancer. This gives the doctor an idea of how the cancer may develop, and how quickly it may grow.

Grade describes how different the cancer cells look from normal cells. Type describes the type of cell the cancer has started growing from.

Your doctor might describe the cancer using the World Health Organisation system. This system uses letters from A–C to explain what the thymus gland tumour looks like under the microscope.

The doctor might also describe the cancer as low- or high-grade:

• Low-grade - the cancer cells tend to grow slowly and look more like normal cells.
• High-grade - the cancer cells tend to grow more quickly and look very abnormal.

Your treatment will depend on the stage and grade of the cancer and your general health. The main treatment for thymus gland cancer is usually surgery. If you have stage 1 thymus gland cancer, this may be the only treatment you need. But chemotherapy and radiotherapy are often used before or after surgery. Sometimes they are used as the first treatment if you can’t have surgery. When chemotherapy and radiotherapy are given together, it’s called chemoradiation.

Surgery

Surgery is used to remove all of the cancer, or as much of it as possible. If the cancer has spread outside the thymus gland, the surgeon may also need to remove nearby areas of tissue around the lungs or around the heart. Surgery is also used to remove cancer that has come back in the same area after previous treatment.

The way the surgeon removes the cancer depends on its size and stage. If the cancer has spread outside the thymus gland, you may need open surgery. But smaller tumours can sometimes be removed using video-assisted thoracic surgery (VATS). During VATS, the surgeon makes a small cut at the base of the neck and uses thin, flexible tubes with a camera and surgical instruments on the end to remove the thymus gland.

If you have VATS, you may only need to stay in hospital overnight. If you have open surgery, you may be in hospital for longer. Your surgeon can explain what to expect.

Radiotherapy and chemoradiation

Radiotherapy uses high-energy rays to destroy cancer cells, while doing as little harm as possible to healthy cells. Radiotherapy is given to reduce the risk of cancer coming back after surgery, or to treat cancer that can’t be removed with surgery.

Chemoradiation, or sometimes radiotherapy alone, is given if you can’t have surgery or if the cancer has spread to other areas of the body. Having chemotherapy and radiotherapy together is more effective than either treatment alone. However, the side effects are also worse during treatment. It’s important that you're well enough to cope with having both treatments together.

You have treatment as a series of short, daily sessions (called fractions) over 4–6 weeks from a machine similar to a large x-ray machine. Radiotherapy only treats the area of the body the rays are aimed at. It doesn’t make you radioactive.

Radiotherapy may also be used to control symptoms such as pain if the cancer has spread to other areas of the body. In this case, you might only need a few days of treatment or even just a single dose.

Side effects of radiotherapy

You may have side effects during radiotherapy. These usually disappear gradually over a few weeks or months after treatment finishes. Your radiotherapy team will let you know what to expect. Tell them about any side effects you have. There are often things they can do to help.

After 2–3 weeks of treatment, the main problem you’re likely to have is difficulty swallowing. This happens because the radiotherapy can make your throat sore and dry. You may also have heartburn or indigestion.

If you find it hard to eat and drink, let your doctor or nurse know. They can give you advice and medication to help. They may refer you to a dietitian for more advice. You may need food supplements to add extra energy and/or protein to your diet. Some supplements can be used to replace meals, and you use others in addition to your normal diet. A few of these products are available from your chemist or the supermarket, but your doctor, nurse or dietitian can also prescribe them for you.

Your treatment area may include parts of the lungs or heart near the thymus gland. Radiotherapy can make these areas sore and swollen. This may make you feel breathless, or give you a dry cough or chest pain. This can start during treatment or in the weeks afterwards. It usually improves with time. If you notice these side effects, tell your doctor. They can give you drugs and treatment to help.

Your radiotherapy team will give you advice about skincare during treatment. It’s common to have a skin reaction in the area of the chest being treated. The skin can become sore and red. This usually starts 2–3 weeks after treatment starts, and may last for 3–4 weeks after treatment ends. If your skin becomes sore, let your radiotherapy team know. They can give you painkillers and advice about caring for your skin until it heals.

Most of these side effects get better after treatment ends. However, sometimes radiotherapy can cause other long-term effects to the lungs or heart. These aren’t as common, but they can happen months or even years after your treatment. Your doctor will explain any risks and how likely they are for you.

We have more information about radiotherapy and coping with its side effects.

Chemotherapy

Chemotherapy uses anti-cancer (cytotoxic) drugs to destroy cancer cells. You may have this treatment to shrink the tumour before having surgery. Chemotherapy is also given after surgery to reduce the risk of cancer coming back. Sometimes chemotherapy is given as the main treatment (alone or as chemoradiation) if you can’t have surgery.

The chemotherapy drug most often used to treat thymus gland cancer is called cisplatin. This drug is given into a vein (intravenously).

Side effects of chemotherapy

The side effects depend on the drug or combination of drugs you are given. Your doctor or nurse will explain any treatment you are offered and what to expect.

Chemotherapy can reduce the number of white blood cells in your blood during treatment. This will make you more likely to get an infection. Your doctor or nurse will give you advice about what to do if this happens.

Chemotherapy can also cause side effects such as feeling tired, a sore mouth, feeling sick (nausea) or being sick (vomiting), diarrhoea and hair loss. Let your doctor or nurse know about any side effects during treatment. They can often give you advice and help to reduce these.

We have more information about coping with the side effects of chemotherapy and about different chemotherapy drugs.

Clinical trials

Cancer research trials are carried out to try to find new and better treatments for cancer. Trials that are carried out on patients are known as clinical trials.

Research into treatments for thymus gland cancer is ongoing, and advances are being made. But because this type of cancer is rare, there may not always be a relevant trial in progress. If there is, you may be asked to take part. Your doctor must discuss the treatment with you so you have a full understanding of the trial and what it means to take part. You may decide not to take part or to withdraw from a trial at any stage. You will still receive the best standard treatment available.

Once your treatment has finished, you will have regular check-ups and possibly tests. These will probably continue for several years.

If you have any problems or notice any symptoms between these times, let your doctor know as soon as possible.

You may have many different emotions, including anger, resentment, guilt, anxiety and fear. These are all normal reactions and are part of the process many people go through in trying to come to terms with their condition.

Everyone has their own way of coping with difficult situations. Some people find it helpful to talk to family or friends, while others prefer to seek help from people outside their situation. Some people prefer to keep their feelings to themselves. There is no right or wrong way to cope, but help is there if you need it. Our cancer support specialists can give you information about counselling in your area.