Cancer that develops in the cells of a testicle is called testicular cancer or cancer of the testis (plural: testes). Usually only one testicle is affected, but in some cases both are affected.
As testicular cancer grows, it can spread to lymph nodes in the abdomen or to other parts of the body, such as the bones, lungs or liver.
Learn more about:
- What types are there?
- The testicles
- Who gets testicular cancer?
- What causes testicular cancer?
- Germ cell neoplasia in situ (GCNIS)
What types are there?
About 90–95% of testicular cancers start in the cells that develop into sperm – these are known as germ cell tumours. Rarely, germ cell tumours can grow outside the testicles in germ cells found in other parts of the body, such as the brain, middle of the chest and back of the abdomen. These tumours are not testicular cancer and are called extragonadal germ cell tumours. They are treated in a similar way to testicular cancer.
Germ cell tumours
There are 2 main types of germ cell tumours: seminoma and non-seminoma.
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seminoma |
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| non-seminoma |
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Sometimes a testicular cancer can include a mix of seminoma cells and non-seminoma cells, or a combination of the different subtypes of non-seminoma cells (mixed tumours). When there are seminoma and non-seminoma cells mixed together, doctors treat the cancer as if it were a non-seminoma cancer.
A small number of testicular tumours start in cells that make up the supportive (structural) and hormone-producing tissue of the testicles. These are called stromal tumours. The 2 main types are Sertoli cell tumours and Leydig cell tumours. They are usually benign, and are removed by surgery.
Rarely, other types of cancer, such as lymphoma or neuroendrocrine tumours, can also involve the testicles. Call Cancer Council 13 11 20 for more information.
The testicles
The testicles are part of the male reproductive system, which also includes the penis, prostate and a collection of tubes that carry sperm. The testicles are also called testes (or a testis, if referring to one).
What the testicles do
The testicles make and store sperm. They also make the hormone testosterone, which is responsible for the development of male characteristics, such as facial hair, a deeper voice and increased muscle mass, as well as sex drive (libido).
Shape and position in the body
The testicles are 2 small egg-shaped glands that sit in a loose pouch of skin called the scrotum. The scrotum hangs behind the penis. A tightly coiled tube at the back of each testicle called the epididymis stores immature sperm.
The epididymis connects the testicle to the spermatic cord, which contains blood vessels, nerves, lymph vessels and a tube called the vas deferens. The vas deferens carries sperm from the epididymis to the prostate gland.
Ejaculation
When an orgasm occurs, millions of sperm from the testicles move through the vas deferens. The sperm then join with fluids produced by the prostate and seminal vesicles to make semen. Semen is ejaculated from the penis through the urethra during sexual orgasm.
The lymphatic system
The lymphatic system helps to protect the body against disease and infection. Working like a drainage system, it removes lymph fluid from body tissues back into the blood. It is made up of a network of thin tubes called lymph vessels connected to groups of small, bean-shaped lymph nodes. Usually, lymph fluid from the testicles drains into lymph nodes in the abdomen (belly).
The male reproductive system
*Not part of the male reproductive system
Who gets testicular cancer?
Testicular cancer is not common, but it is the most commonly diagnosed cancer in men aged 20–39 (apart from common skin cancers). About 960 men in Australia are diagnosed with testicular cancer each year, which is about 1% of all cancers in men.
Anyone with a testicle can get testicular cancer – men, transgender women, non-binary people and people with intersex variations. For information specific to you, speak to your doctor and see LGBTQI+ people and cancer.
What causes testicular cancer?
The causes of testicular cancer are largely unknown, but certain factors may increase your risk of developing it. Talk to your doctor if you are concerned about any of the following risk factors.
Personal history
Having germ cell neoplasia in situ (GCNIS) increases the risk of developing testicular cancer. If you have previously had cancer in one testicle, you are also more likely to develop cancer in the other testicle than someone who has not had testicular cancer.
Undescended testicles
Before birth, testicles develop inside the abdomen. By birth, or within the first 6 months of life, the testicles should move down into the scrotum. If the testicles don’t descend by themselves, doctors may perform an operation to bring them down.
Although this reduces the risk of developing testicular cancer, people born with undescended testicles are still more likely to develop testicular cancer than those born with descended testicles.
Family history
If your father or brother has had testicular cancer, you are slightly more at risk of developing testicular cancer. But family history is only a factor in a small number (about 2%) of people who are diagnosed with testicular cancer. If you are concerned about your family history of testicular cancer, you can ask your doctor for a referral to a specialist called a urologist.
Infertility
Having difficulty conceiving a baby (infertility) can be associated with testicular cancer.
HIV and AIDS
There is some evidence that people with HIV (human immunodeficiency virus) and AIDS (acquired immune deficiency syndrome) have an increased risk of testicular cancer.
Physical features
Some people are born with an abnormality of the penis called hypospadias. This causes the urethra to open on the underside of the penis, rather than at the end. People with this condition are at an increased risk of developing testicular cancer.
Cannabis use
There is some evidence linking regular cannabis use with the development of testicular cancer.
Intersex variations
The risk of testicular cancer is higher in people with some intersex variations, such as partial androgen insensitivity syndrome, particularly when the testicles remain in the abdomen. For more on this, see LGBTQI+ people and cancer.
Germ cell neoplasia in situ (GCNIS)
Most testicular cancers begin as a condition called germ cell neoplasia in situ (GCNIS). This was previously called intratubular germ cell neoplasia (ITGCN).
In GCNIS, the cells are abnormal, but they haven’t spread outside the area where the sperm cells develop. GCNIS is not cancer but it may develop into cancer after many years.
GCNIS has similar risk factors to testicular cancer.
It is hard to diagnose because there are no symptoms. Although an ultrasound scan may suggest GCNIS, it can only be diagnosed by testing a tissue sample. This may be through a needle biopsy or surgery to remove the testicle.
Once diagnosed, some cases of GCNIS will be carefully monitored (active surveillance). Other cases will be treated with radiation therapy or surgery to remove the testicle.
→ READ MORE: Testicular cancer symptoms
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Key resource
Download a PDF booklet on this topic.
More resources
Dr Benjamin Thomas, Urological Surgeon, The Royal Melbourne Hospital and The University of Melbourne, VIC; A/Prof Ben Tran, Genitourinary Medical Oncologist, Peter MacCallum Cancer Centre, Walter and Eliza Hall Institute of Medical Research and The University of Melbourne, VIC; Dr Nari Ahmadi, Urologist and Urological Cancer Surgeon, Chris O’Brien Lifehouse, NSW; Helen Anderson, Genitourinary Cancer Nurse Navigator, Gold Coast University Hospital, QLD; Anita Cox, Youth Cancer – Cancer Nurse Coordinator, Gold Coast University Hospital, QLD; Dr Tom Ferguson, Medical Oncologist, Fiona Stanley Hospital, WA; Dr Leily Gholam Rezaei, Radiation Oncologist, Chris O’Brien Lifehouse and Royal Prince Alfred Hospital, NSW; Dheeraj Jain, Consumer; Amanda Maple, 13 11 20 Consultant, Cancer Council SA; Jessica Medd, Senior Clinical Psychologist, Department of Urology, Concord Repatriation General Hospital and Headway Health, NSW.
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