About Cancer
Germ cell tumours develop in germ cells. These are the cells in the body that develop into sperm and eggs. Germ cell tumours most often develop in the or testicle because this is where most germ cells are.
But germ cells can sometimes be left behind in other parts of the body from when you developed in the . So these tumours can develop anywhere in your body where there are germ cells.
Germ cell tumours that grow outside the ovary or testicle are very rare. Doctors call them extragonadal germ cell tumours (EGGCT). The mediastinum is the most common place for extragonadal tumours in adults.
The mediastinum is the area in the centre of the chest, between the lungs. It contains the:
windpipe ()
food pipe ()
large main
the that surround the heart
Doctors aren’t certain how germ cell tumours develop in the mediastinum. There are some theories about how the cells get outside the testicle and ovary.
These include the following. The cancer develops:
from very early cells that became misplaced during our development in the womb
in the testicle or ovary and spread at a very early stage, but the original cancer has either disappeared or is too small to find
These tumours are much more common in males than females. You can get mediastinal germ cell tumours at any age. But they are most common between the ages of 20 and 40.
Doctors use different names to describe the different types of germ cell tumours. The name describes what the tumour looks like under the microscope.
Benign means non cancerous. An example of a benign germ cell tumour is a mature teratoma.
Mature teratomas are the most common type of ovarian germ cell tumour. They are often called an ovarian dermoid .
Malignant means cancerous. Malignant germ cell tumours are split into 2 main groups:
seminoma germ cell tumours (in females these are called dysgerminomas)
non seminoma germ cell tumours (in females these are called non dysgerminomas)
Malignant non seminoma tumours include:
immature teratomas
yolk sac tumours
carcinomas
Read more about the types of germ cell tumours
Many people with a benign tumour in the mediastinum don’t have any . The doctor might spot the tumour on a you had for another reason.
Most people with a cancerous mediastinal tumour have symptoms which might include:
shortness of breath
pain in the chest
a cough
raised temperature
weight loss
difficulty breathing from a blockage in the airway
hoarse voice
Doctors use various tests to diagnose mediastinal germ cell tumours. These might include:
a chest X-ray
to check for substances called
a – this test uses a camera to look in your chest and take
a
an of the ovaries or testicles to check for signs of cancer
an
Tumour markers are substances that are produced by:
the cancer, or
by other cells in response to the cancer
Tumour markers are usually proteins that can be found in the blood, urine or body tissues.
Germ cell tumours can make the following tumour markers:
alpha feta protein (AFP)
Not all germ cell tumours make these tumour markers. You could have a cancer without raised marker levels. Raised levels are more common in some types of germ cell tumours than others.
Your doctor will also do a blood test to measure your LDH level (lactate dehydrogenase).
You have these blood tests during and after your treatment. Doctors use the levels of these markers to:
help stage your cancer
show how well treatment works
look for signs of the cancer coming back
You might have a test to look for in your blood, if you haven't had a biopsy. This looks for acetylcholine receptor binding (AChR) antibody.
Find out more about the different types of tests and scans
Your treatment depends on what type of germ cell tumour you have. Below we describe the treatment for the 3 main types of mediastinal germ cell tumours:
The type of surgery you have depends on:
where your tumour is in the chest
whether your tumour is close to any important structures such as major blood vessels, your heart or lungs
the size of your tumour
Surgery for mediastinal germ cell tumour is a major operation. There are different types of operation.
You have a thoracotomy and a sternotomy as open surgery. This means the surgeon makes one large cut (incision) in your chest. Or you might have a type of keyhole surgery. This means your surgeon makes several small cuts in your chest.
You have this as open surgery. Your surgeon makes a cut that runs around the side of the chest. Sometimes the cut may only be a few centimetres long. But it can also be longer and run from under the nipple around to your back under the shoulder blade.
You have this as open surgery. Your surgeon makes a cut in the front of your chest. They cut through the breast bone (sternum). The cut runs from the base of the neck down to the top of your .
You might have keyhole surgery to remove small tumours. The medical name for this operation is video assisted thoracoscopic surgery (VATS). The surgeon makes up to 3 small cuts on the side of your chest. They use a long, bendy tube called a .
The thoracoscope connects to a fibre optic camera. This shows pictures of the inside of the chest on a video screen. The surgeon puts the surgical instruments into the other cuts to remove the tumour.
Diagram showing video assisted thoracoscopy
Get general information about surgery for cancer
After treatment, you will have regular check ups. And you have tests to check for signs that the cancer is coming back.
Tests will include chest X-rays, CT scans and blood tests to check for any changes in the level of the tumour markers.
Coping with a diagnosis of a rare cancer can be especially difficult. Being well informed about your cancer and its treatment can help. It 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.
You can call our nurse freephone helpline on 0808 800 4040. They are available from Monday to Friday, 9am to 5pm. Or you can send them a question online.
Last reviewed: 14 Apr 2025
Next review due: 14 Apr 2028
Treatments can include surgery, radiotherapy and drug treatments (such as chemotherapy, hormone therapy or targeted cancer drugs). Find out about treatments and how to cope with side effects.
Germ cell tumours are growths that develop from germs cells. These are the cells that become sperm or eggs. The type of germ cell tumour you have depends on where in the body the tumour is and what it looks like under a microscope.
There are things you can do to help you feel more in control of your health when preparing for treatment. This is called prehabilitation or prehab.
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