Find out about the causes of testicular cancer.
In the UK around 2,200 men are diagnosed with testicular cancer each year. That's about 1 out of every 100 cancers (1%) diagnosed in men.
We don't know what causes most testicular cancers. But some factors can increase your risk of getting it.
What a risk factor is
Anything that can increase your risk of getting a disease is called a risk factor.
Different cancers have different risk factors. Having one or more of these risk factors doesn't mean you will definitely get that cancer.
As testicular cancer is rare, the risk of developing it is small even if you do have any risk factors.
Risk factors for testicular cancer
Having undescended testicles (cryptorchidism) increases the risk of testicular cancer. This is the most important risk factor for this cancer.
In the womb, the testicles develop in a male baby's abdomen. They usually move down into the scrotum at birth or in the first year of life.
If they move down later or need surgery to bring them down, they are called undescended testicles.
In most men with undescended testicles, the testicles move down by the age of puberty. Some men have surgery to bring them down. The risk is greater in men:
- where the condition isn’t corrected
- who haven't had surgery by the age 11 to 13
Carcinoma in situ (CIS) means that there are abnormal cells in the testicle. It isn't cancer. There is no lump and usually no other symptoms.
If left untreated CIS develops into cancer in about half (50%) the men who have it.
CIS is most often found when a man has a testicular biopsy to check for infertility.
It can be treated by removing the testicle to prevent testicular cancer from developing.
Men with fertility problems have an increased risk of testicular cancer.
The key problems are:
- low semen concentration
- sperm that does not move around as much as normal
- a high proportion of abnormal sperm
We are still not sure why fertility problems and testicular cancer are linked.
It may be because testicular cancer and fertility problems share some of the same risk factors.
If you have had testicular cancer already, your risk of developing a cancer in the other testicle is increased by 12 to 18 times.
This number sounds quite high but testicular cancer is rare. Only a small percentage of men will develop cancer in the remaining testicle.
It is important to attend follow up appointments after treatment.
Brothers or sons of men who have had testicular cancer have an increased risk of getting it.
- Men whose father had testicular cancer are around 4 times more likely to develop it
- Men with a brother who had testicular cancer are around 8 times more likely to develop it
Some of the increase in risk is thought to be caused by changes in certain genes.
Men who are born with an abnormality of the penis and urethra called hypospadias are more likely to develop testicular cancer.
Men who have an inguinal hernia are more likely to develop testicular cancer.
An inguinal hernia is a lump in the groin area caused by a part of the bowel (intestine) slipping through a weakness in the tummy (abdominal) wall.
Men with HIV or AIDS have an increased risk of testicular cancer. But most cases of testicular cancer are not linked to being HIV positive.
Testicular cancer is more likely to be diagnosed in some racial and social groups.
In the UK, white men have a higher risk of testicular cancer than men from other ethnic groups
Calcium specks in the testicles is called testicular microlithiasis. These are often found by chance. Doctors usually diagnose this with an ultrasound scan when checking testicular symptoms such as pain or swelling.
Testicular cancer is not increased in men with microlithasis who are otherwise healthy. But men who have it along with other testicular cancer risk factors (such as fertility problems or undescended testicle) have an increased risk.
It is difficult to know how many men have it. It may affect between 2 and 6 out of every 100 men (2% to 6%).
There are no guidelines on how your doctor should monitor you if you have calcium specks in the testicle. Your GP should talk the situation through with you. Then you can both make a decision based on what is best in your case.
Men who are taller than average have an increased risk of testicular cancer.
Between the 1940s and early 1970s, doctors used to prescribe a drug called diethylstilbestrol (DES) to some pregnant women with a history of pregnancy problems. There has been a lot of research to see if exposure to DES in the womb increases the risk of testicular cancer. But a meta-analysis of the research didn't find a significantly higher incidence of testicular cancer in DES exposed boys. There is a higher frequency of undescended testicle in boys born to DES mothers. Undescended testicle is a risk factor for testicular cancer, so there could be an indirect link.
Twins have an increased risk of testicular cancer, especially if they are both boys. But as testicular cancer is so rare the risk is still low.
Other possible causes
Stories about potential causes of cancer are often in the media. It isn’t always clear which ideas are supported by good evidence.
You might hear about possible causes we haven’t included here. This is because there is no evidence about them or because the evidence isn’t clear.