Testicular cancer risks and causes

Testicular cancer is a relatively rare disease. Around 2,200 cases are diagnosed in the UK each year. That's about 3 out of every 200 cancers diagnosed in men.

The most important risk factor for testicular cancer is undescended testicle (cryptorchidism). In the womb, the testicles develop in a male baby's abdomen. They usually move down into the scrotum at birth, or within the first year of life. If they move down later, or need surgery to bring them down, this is called undescended testicle. Some studies show that men whose testicles move down, or have surgery to bring them down, by the age of puberty are 4 times more likely to develop testicular cancer than other men. As testicular cancer is rare, the risk is still small. But in men where the condition is not corrected by the age of 11, the risk of testicular cancer is increased by up to 32 times.

Some men have undescended testicle on one side only. A review of published studies showed that in this situation there is an increased risk in that testicle and a smaller increase in risk in the other testicle.

Men who are born with an abnormality of the penis and urethra called hypospadias are twice as likely to develop testicular cancer as men in the general population.

Brothers or sons of men who have had testicular cancer have an increased risk of testicular cancer. One explanation could be a testicular cancer gene abnormality. Changes in a gene called TGCT1 were found by researchers at the Institute of Cancer Research in February 2000. The abnormal gene is on the X chromosome and so is inherited from the mother and not the father. The researchers carrying out this work think there could be 2 other testicular cancer genes that we haven't found yet. They think that up to 1 in 5 (20%) of testicular cancers could be due to inherited faulty genes.

A trial is being carried out to try to find genes that may increase the risk of developing cancer. It is called the UK genetics of testicular cancer study. Over 3,000 men who have had testicular cancer will give a small sample of blood. Researchers will then look at the samples to find any possible genes that could increase the risk of testicular cancer. The trial will end in 2016 so the results are not likely to be available for many years.

Men who have family members with breast cancer, melanoma or undescended testicle have an increased risk of testicular cancer.

Men who have had testicular cancer have a 12 times increase in their risk of developing a second testicular cancer in the other testis. So it is important for them to attend follow up appointments after treatment.

Carcinoma in situ (CIS) means that there are abnormal cells in the testicle. But they are completely contained and so cannot spread, as cancer cells can. Carcinoma in situ of the testicle is not cancer. But if left untreated, it will develop into cancer in about half the men who have it (50%). There is no lump and usually no other symptom. CIS is most often found when a man has a testicular biopsy to investigate infertility. CIS can be treated by removing the testicle, to prevent a testicular cancer from developing.

For some time, doctors have suspected that testicular cancer was linked to fertility problems and poor sperm quality. Studies have confirmed that men with fertility problems have an increased risk of testicular cancer. The problems they identified were low semen concentration, sperm that did not move around as much as normal, or a high proportion of abnormal sperm.

There is a significant link between infertility and testicular cancer risk. But as the overall risk of testicular cancer is small, this means there is only really a small increase in risk for men with fertility problems. Out of 32,000 men with fertility problems in one Danish study, they found that 89 testicular cancers had been diagnosed.

A combined analysis of published studies has shown that men with HIV or AIDS have an increased risk of testicular cancer.

Testicular cancer is more common in some racial and social groups. Five times as many white men as black men in the United States get testicular cancer. In the UK, a study has shown that white men have a higher risk of testicular cancer than men from other ethnic groups. We do not know why this is.

As they get older, some men develop small areas of calcium in the testes called microlithiasis. Studies have shown that men who have these calcium specks are more likely to develop testicular cancer than men who do not have them. But their risk of testicular cancer is still small.

There is evidence that men who are taller than average have an increased risk of testicular cancer and men who are shorter than average have a reduced risk.

There is no known link between injury or sporting strains and testicular cancer. But an injury often causes swelling and lumps in the testicle and this can make a tumour difficult to spot. If you have injured your testicles and have any swelling, go to your GP for a check up.

Some research evidence shows that the levels of certain hormones in the mother in early pregnancy may affect the risk of testicular cancer in their sons. One study showed that higher levels of a hormone known as dehydroepiandrosterone sulphate gave a lower risk of testicular cancer. But higher levels of androstenedione and oestradiol may increase the risk. One study showed that sons of women with lower levels of oestradiol and oestriol in early pregnancy had a higher risk of undescended testicle than the general population. More studies are needed to see if mother's hormone levels during pregnancy can really affect testicular cancer risk. 

Men whose mothers had bleeding during pregnancy have a higher risk of testicular cancer. But men who have older brothers and sisters have a lower risk. An increased risk of testicular cancer has been shown for men who had an unusually high or low birth weight.

Twins have an increased risk of testicular cancer, especially if they are identical or if they are both boys. But as testicular cancer is so rare the risk is still low.

There is no known link between vasectomy and testicular cancer. Early research suggested a link, but this has since been shown to be untrue.