What is thymus gland cancer?

Thymus gland cancer is rare and the cause is not known. The thymus gland is in the chest, between the lungs and behind the breastbone. It makes white blood cells called T lymphocytes.

Types of thymus gland cancer

There are two main types of thymus gland cancer:

  • Thymoma – this cancer is more common and is usually diagnosed in people aged between 40 and 60. Some thymomas grow very slowly and may not have spread outside the thymus when they are diagnosed. Others may have spread within the chest area.
  • Thymic carcinoma – this cancer can develop in people of any age and usually grow more quickly. They have often spread outside the thymus when they are diagnosed.

Other types of cancer that can affect the thymus gland include lymphomas, germ cell tumours and neuroendocrine tumours. These cancers are all treated in different ways.

Symptoms of thymus gland cancer

Symptoms of thymus gland cancer may include:

  • chest pain
  • a cough that does not go away
  • coughing up blood
  • becoming breathless or wheezy
  • difficulty swallowing
  • a hoarse voice.

These symptoms can be caused by other conditions, but it is important to have them checked by your doctor.

Sometimes thymus cancer has no symptoms, but is found when people are having tests for something else. For example, it might show up when someone has a routine chest x-ray. Or it may show up on a CT scan in someone who has myasthenia gravis.

Causes of thymus gland cancer

We do not know exactly what causes thymus cancer.

Having a rare inherited condition called MEN1 (multiple endocrine neoplasia type 1) can be linked with an increased risk of some cancer types. These can include thymus cancers.

Thymomas are linked with different autoimmune conditions.

Diagnosis of thymus gland cancer

If you have symptoms of thymus cancer, you usually start by seeing your GP. They will refer you to a hospital specialist if they:

  • are unsure what the problem is
  • think your symptoms may be caused by cancer.

At the hospital, the specialist doctor will ask you about your symptoms and general health before examining you. You may have the following tests:

  • 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 scan

    A CT scan takes a series of x-rays, which build up a three-dimensional picture of the inside of the body.

  • PET-CT scan

    A PET-CT scan gives more detailed information about the part of the body being scanned.

  • MRI scan

    An MRI scan uses magnetism to build up a detailed picture of areas of your body.

Further tests for thymus gland cancer

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) examines the biopsy samples under a microscope. The results tell your doctor:

  • the type of thymus cancer you have
  • how the cells look when they are examined under a microscope.

You may have the following tests:

  • CT-guided needle biopsy

    The doctor (radiologist) uses a CT scan (see above) to help them find the exact area to take the biopsy from.

    They give you an injection of local anaesthetic into the skin to numb the area. Then they pass a thin needle through your skin into the thymus area and remove a sample of cells (biopsy). You may feel some pushing when they take the biopsy. It only takes a few minutes.

  • Mediastinoscopy

    If the doctor cannot get a sample of cells using a needle biopsy, you may have this test. It allows the doctor to examine the area in the centre of your chest (mediastinum). You have it under a general anaesthetic, so you may need to stay in hospital overnight.

    The doctor makes a small cut in the skin at the base of your neck. They pass a long, thin tube through the cut into your chest. The tube has a camera on the end. This shows a picture of the area on a screen. The doctor can take samples of tissue from the thymus through the tube.

  • Thoracoscopy

    This test is like a mediastinoscopy. It can be done under a general anaesthetic. Or sometimes you have a local anaesthetic to numb the area and a sedative to make you drowsy.

    The doctor makes one or two small cuts in your chest. They pass a thin tube called a thoracoscope through one of the cuts into your chest and take a sample of tissue from the thymus. Sometimes doctors use a video camera attached to the tube so they can see the area more clearly. This is called video-assisted thoracoscopy.

    If any fluid has collected in the area, they can remove it by putting in a long tube that drains the fluid into a bottle (chest drain). A nurse usually takes the chest drain out after 1 to 3 days. You need to stay in hospital until it is taken out.

Staging and grading of thymus gland cancer

The results of your tests help your doctors find out more about the size and position of the cancer and whether it has spread. This is called staging.

A doctor decides the grade of the cancer by how the cancer cells look under the microscope. This gives an idea of how quickly the cancer might grow or spread.

Knowing the stage and grade of thymus gland cancer helps doctors decide the best treatment for you.

Treatment for thymus gland cancer

A team of specialists will meet to discuss the best possible treatment for you. This is called a multidisciplinary team (MDT).

Your cancer doctor or specialist nurse will explain the different treatments and their side effects. They will also talk to you about the things you should consider when making treatment decisions.

You may have some treatments as part of a clinical trial.

Your treatment will depend on:

  • the type of tumour
  • the stage and grade of the tumour
  • your general health.

For most people, the aim of treatment is to remove or destroy the cancer and to reduce the chance of the cancer coming back.

The main treatments for thymus gland cancer are:

Surgery

Surgery is the main treatment for thymus cancer. The surgeon removes all of the thymus, or as much of it as possible. This operation is called a thymectomy. The type of operation you have depends on the stage of the cancer.

Radiotherapy

Radiotherapy uses high-energy rays to destroy cancer cells, while doing as little harm as possible to normal cells. If you have stage 1 thymoma, you are unlikely to need radiotherapy. Most people with thymic carcinoma will need radiotherapy after surgery. You have radiotherapy in short, daily sessions called fractions over 4 to 6 weeks,

Chemotherapy

Chemotherapy uses anti-cancer (cytotoxic) drugs to destroy cancer cells. You may have it before surgery, to shrink the cancer and make surgery easier. It can also be given after surgery, to reduce the risk of cancer coming back. It can also be given on its own or with radiotherapy (called chemoradiation) as your main treatment, if surgery is not possible.

The most common chemotherapy drugs for treating thymus gland cancer are:

We have more information about having chemotherapy and possible side effects.

Targeted therapy or immunotherapy drugs

Researchers are trying to find out how helpful targeted therapies and immunotherapy drugs are in treating thymus cancers. Your doctor may recommend a clinical trial with one of these drugs after you have already had other treatments.

Targeted therapy drugs interfere with the way cancer cells signal to or interact with each other. Some of them stop the tumour from making new blood vessels.

Some trials are looking at whether immunotherapy drugs are helpful in treating thymic cancers. These drugs help stimulate your immune system to recognise and destroy cancer cells.

After thymus gland cancer treatment

You will have regular follow-up appointments after treatment. These may continue for several years. You may have tests, such as CT scans.

After treatment, some people are cured of thymus gland cancer. But for others, cancer may come back after treatment. If this happens, you may be able to have further treatment.

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

Well-being and recovery

Even if you already have a healthy lifestyle, you may choose to make some positive lifestyle changes after treatment.

Making small changes such as eating well and keeping active can improve your health and wellbeing and help your body recover.

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