About Cancer
Germ cell tumours develop from 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).
Doctors use different names to describe the different types of germ cell tumours. The name describes:
whereabouts in the body it started - such as ovarian or testicular
what the tumour looks like under the microscope
Germ cell tumours can start in the:
testes
ovaries
- mediastinal tumour
back of the - retroperitoneal tumour
brain - pineal region tumour
lower - sacrococcygeal tumour
The type of germ cell tumour you have depends on where in the body the is. And what it looks like under a microscope. Some germ cell tumours are non cancerous (benign). And some are cancerous (malignant):
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)
Seminomas are sometimes called pure seminomas. They only contain one type of cell. Some germ cell tumour contain both seminoma cells and non seminoma cells. Doctors usually class and treat these as non seminoma tumours.
Malignant non seminoma tumours include:
immature teratomas
yolk sac tumours
carcinomas
Some non seminomas develop from just one type of . And some develop from a mixture of cell types. So, for example, a tumour can contain a mix of some teratoma cells and some embryonal carcinoma cells.
Men can develop testicular germ cell tumours. Most testicular cancers are germ cell tumours. The 2 main types of testicular germ cell tumours are seminomas and non seminomas.
Read all about testicular germ cell tumours
Women can develop ovarian germ cell tumours. Most of these are benign. But some are cancerous. The most common type of germ cell tumour is called a mature teratoma or dermoid cyst. These are usually non cancerous. About 95 out of 100 germ cell tumours are non cancerous.
Mature teratoma is the most common type of ovarian germ cell tumour. It is often called an ovarian dermoid cyst. It is benign.
Go to more information about ovarian germ cell tumours
Cancers that develop from germ cells in other parts of the body are rare. The medical name for germ cell tumours that develop outside of the ovaries or testicles is extragonadal germ cell tumour (EGGCT).
Extragonadal germ cell tumours can start in different parts of the body:
The mediastinum is the area between the lungs, which contains the heart. It is the most common place for extragonadal tumours in adults.
Read about mediastinal germ cell tumours and their treatment
Pineal region tumours are rare brain tumours. The pineal gland is in the middle of the brain, just behind the brain stem.
There are different types of pineal region tumours. The most common type is a type of germ cell tumour. This is called a germinoma.
Read more about pineal region tumours
Retroperitoneal germ cell tumours start in the retroperitoneum. The retroperitoneum is the area at the back of the tummy (abdomen). It is where there are organs such as the kidneys, pancreas, bladder and some major blood vessels.
The treatment for retroperitoneal germ cell tumours is similar to testicular germ cell tumours.
Read about treatment for testicular germ cell tumours
Sacrococcygeal germ cell tumours develop at the bottom of the spine by the tailbone (coccyx). This area is called the sacrococcygeal region.
Although this is the most common type of germ cell tumour in children, it is very rare in adults. Some babies are diagnosed with a sacrococcygeal tumour before they are born, during a pregnancy (antenatal) scan. These tumours are often benign.
Your treatment depends on:
where the tumour is
the size and whether it has spread (the stage)
the type of germ cell tumour
The main treatments are surgery and chemotherapy.
You usually have surgery to remove germ cell tumours. This might be all the treatment you need if the tumour is benign, small and easy to remove.
Find out more about having surgery
You might have chemotherapy after surgery. Germ cell tumours generally respond very well to chemotherapy. Most people are cured. Even cancers that have spread are still very treatable with chemotherapy.
You can read more about the treatment for your type of germ cell tumour at the links above.
Find out more about having chemotherapy
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: 10 Apr 2025
Next review due: 10 Apr 2028
Testicular cancer is cancer that develops in the testicles, which are part of a man's reproductive system.
Germ cell ovarian tumours begin in the ovarian cells that develop into eggs. They can be non cancerous (benign) or cancerous (malignant).
The mediastinum is the area in the centre of the chest, between the lungs. Mediastinal germ cell tumours are a type of tumour that grow in the mediastinum. They develop in a type of cell called germ cells. There are different types of mediastinal germ cell tumours.
Coping with cancer can be difficult. There is help and support available. Find out about the emotional, physical and practical effects of cancer and how to manage them.
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.
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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