Thymus gland cancer is cancer that starts in the thymus gland. This information is about two types of thymus glad cancer, called thymoma and thymic carcinoma.
What is thymus gland cancer?
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 tumors and neuroendocrine tumors. These are treated in different ways and we can send you more information about them.
The thymus gland
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. It shrinks and is replaced by fat and scar tissue.
Diagram showing the position of the thymus gland
Conditions linked to thymus gland cancer
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.
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.
Another condition linked to thymus gland cancer is hypoglobulinemia. People with hypoglobulinemia 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 hypoglobulinemia.
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 of thymus gland cancer
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.
Diagnosing thymus gland cancer
If you have symptoms, you usually start by seeing your PCP. 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:
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 (computerized tomography) scan
A CT scan takes a series of x-rays that build up a three-dimensional picture of the inside of the body. The scan is painless and takes 10–30 minutes. CT scans use a small amount of radiation, which will be very unlikely to harm you and will not harm anyone you come into contact with. You may 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. If you’re allergic to iodine or have asthma, you could have a more serious reaction to the injection, so it’s important to let your doctor know beforehand.
MRI (magnetic resonance imaging) scan
This test is similar to a CT scan, but it uses magnetism instead of x-rays to build up a detailed picture of areas of your body. Before the scan, you may be asked to complete and sign a checklist. This is to make sure it’s safe for you to have an MRI scan.
Before having the scan, you’ll be asked to remove any metal belongings, including jewelry. Some people are given an injection of dye into a vein in the arm. This is called a contrast medium and can help the images from the scan to show up more clearly. During the test, you will be asked to 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 during the scan. It’s also noisy, but you’ll be given earplugs or headphones.
This is a combination of a CT scan and a PET (positron emission tomography) scan. A CT scan takes a series of x-rays that build up a three-dimensional picture of the part of the body being scanned. A PET scan uses low-dose radiation to measure the activity of cells in different parts of the body. PET/CT scans are a newer type of scan, and you may have to travel to a specialist center to have one.
You won't be able to 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. After at least an hour, you can have the scan. It usually takes about 30 minutes.
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 specializes in analyzing 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 anesthetic. Then they use a needle to collect cells from the thymus gland. During this test they use CT scans to guide the needle.
If the doctor can’t get a sample of cells using a needle biopsy, you may have this test under a general anesthetic. 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.
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 anesthetic and sedation or under a general anesthetic.
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.
Staging of thymus gland cancer
The stage of a tumor describes its size and whether it has spread. Knowing the stage helps doctors decide on the best treatment for you.
The cancer is inside the thymus gland and has not spread.
The cancer has spread through the outer lining of the thymus gland or into the fat around it.
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.
The cancer has spread widely into the lining of the lungs (pleura) and the lining of the heart (pericardium).
The cancer has spread to other distant organs, such as the liver.