It is not known exactly what causes testicular cancer. Although it is still quite rare, the number of men who develop it has been steadily increasing for the past few years. The reason for this is not known, but research is going on all the time into possible causes.
Testicular cancer is more common in men who have a testicle which has failed to descend.
In the unborn child the testicles develop inside the abdomen between the kidneys and descend into the scrotum at birth or during the first year of life. If they move down later, or need surgery to bring them down, this increases the risk of testicular cancer. A particular gene has been found in many men with testicular cancer. It is possible that this gene is inherited and may be the reason why testicular cancer sometimes occurs in brothers or sons of men who have had the disease. Testicular cancer is more common in white people than black people.