On this page: The testicles | What is testicular cancer? | What types are there? | What are the risk factors? | How common is it? | What are the symptoms?
The testicles are part of the male reproductive system. They are also called testes (or a testis, if referring to one).
The two small, egg-shaped glands sit behind the penis in a pouch of skin called the scrotum. They produce and store sperm. They also produce the male hormone testosterone, which is responsible for the development of male characteristics such as facial hair growth, a deeper voice than women, muscle development, sexual drive (libido), and the ability to have an erection.
A tubular structure called the epididymis is attached to the back of each testis. The epididymis stores immature sperm and is attached to the spermatic cord, which runs from each testicle through the groin region into the pelvis (lower abdominal cavity). The spermatic cord contains blood vessels, nerves, lymph vessels and a tube called the vas deferens, which carries sperm from the epididymis to the prostate gland.
Seminal vesicles, prostate gland and lymph nodes
Two sac-like pouches called seminal vesicles sit above the prostate gland. The seminal vesicles and prostate gland produce fluid which, along with sperm from the testicles, makes up a large part of semen. Semen is ejaculated from the penis during sexual climax.
There are many lymph nodes (glands) and lymphatic vessels around the testicles and in the abdomen. These are part of the lymphatic system and are important for resisting and fighting disease (immunity). The nodes and vessels also drain lymphatic fluid (lymph) from the tissues back into the bloodstream.
What is testicular cancer?
Cancer that develops in a testicle is called testicular cancer or cancer of the testis. Usually only one testicle is affected, but in some cases both are affected. Most testicular cancers start in the cells that develop into sperm – these are called germ cells.
Sometimes testicular cancer can spread to lymph nodes in the abdomen, or to other parts of the body.
What types are there?
The most common testicular cancers are called germ cell tumours. There are two main types, which look different under a microscope.
Germ cell tumours
- tends to develop more slowly than non-seminoma cancers
- usually occurs in men aged 25–45, but also occurs in men over 60
- rarer cancers that tend to develop more quickly than seminoma cancers
- more common in younger men in their late teens and 20s
- made up of subtypes such as teratomas, yolk sac tumours, choriocarcinomas and embryonal carcinomas
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 two main types are Sertoli cell tumours and Leydig cell tumours. They are usually benign and are removed by surgery.
Other types of cancer, such as lymphoma, can also involve the testicles. For information, call Cancer Council 13 11 20.
Intratubular germ cell neoplasia
Some germ cell cancers begin as a condition called intratubular germ cell neoplasia (ITGCN or IGCN). This is a non-invasive precursor to testicular cancer because the cells are abnormal, but they haven’t spread outside the area where the sperm cells develop.
There is about a 50% risk that ITGCN will progress into testicular cancer within five years. ITGCN has similar risk factors to testicular cancer.
ITGCN is difficult to diagnose because there are no symptoms and it can only be found by biopsy. However, about 5–10% of men diagnosed with testicular cancer have ITGCN. Treatment includes watchful waiting and chemotherapy.
What are the risk factors?
The causes of testicular cancer are unknown, but certain factors may increase a man’s risk of developing it:
Men who have previously had cancer in one testicle are about 25 times more likely to develop cancer in the other testicle. ITGCN is also a risk factor (see above).
Before birth, testicles develop inside a male baby’s abdomen. By birth, or within the first year of life, the testicles usually move down into the scrotum.
If the testicles don’t descend by themselves, doctors perform an operation to bring them down. Although this reduces the risk of developing testicular cancer, men born with undescended testicles are still about 16 times more likely to develop testicular cancer than men born with descended testicles.
Sometimes gene mutations are passed on in families. A man with a father or brother who has had testicular cancer is slightly more at risk of cancer. However, family history is only a factor in a small number (about 2%) of men 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 family cancer clinic, genetic counsellor and/or a urologist, who can provide information about the most suitable screening for you and your family members.
Having difficulty conceiving a baby (infertility) is associated with ITGCN (see above), undescended testicles and genetic abnormalities. Due to the shared risk factors with testicular cancer, infertility is also considered a risk factor for testicular cancer.
HIV and AIDS
There is some evidence that men with HIV (human immunodeficiency virus) and AIDS (acquired immune deficiency syndrome) have an increased risk of testicular cancer, although the reasons are unknown.
Some congenital defects
Some men 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. Men with this condition are about twice as likely to develop testicular cancer.
There is no known link between testicular cancer and injury to the testicles, sporting strains, hot baths, wearing tight clothes, sexual activity or having a vasectomy.
How common is it?
Testicular cancer is not a common cancer, but it is the most commonly diagnosed cancer after skin cancer in men aged 18–39. About 800 men are diagnosed with testicular cancer in Australia each year, accounting for about 1% of all cancers in men. It occurs most often in men aged 25–40.
What are the symptoms?
In some men, testicular cancer does not cause any noticeable symptoms, and it may be detected during tests for other conditions. Other men may notice one or more of the following symptoms:
- swelling or a lump in the testicle, which are both usually painless
- a feeling of heaviness in the scrotum
- a change in the size or shape of the testicle (e.g. hardness or swelling)
- a feeling of unevenness between the testicles
- aches or pain in the lower abdomen, testicle or scrotum
- enlargement or tenderness of the breast tissue (gynaecomastia)
- back pain
These symptoms don’t necessarily mean you have testicular cancer. They are common to other conditions, such as cysts, which are harmless lumps. However, if you have any of these symptoms, you should have them checked by your doctor without delay.
"I’d been feeling unwell and strangely fatigued and, after some tests, the doctor diagnosed me with testicular cancer." – Matt
Reviewed by: A/Prof Declan Murphy, Urologist, Director of Genitourinary Oncology, Peter MacCallum Cancer Centre, VIC; Gregory Bock, Urology Cancer Nurse Coordinator, WA Cancer & Palliative Care Network, WA; A/Prof Martin Borg, Radiation Oncologist, Adelaide Radiotherapy Centre, SA; A/Prof Joseph McKendrick, Medical Oncologist, Eastern Oncology, Eastern Health and Monash University, VIC; Caitriona Nienaber, 13 11 20 Consultant, Cancer Council Western Australia, WA; Ben Peacock, Consumer; and Deb Roffe, Cancer Council Nurse, Cancer Council SA.