The causes of testicular cancer are unknown. The greatest risk is for men born with an undescended testicle(one that remains in the abdominal cavity rather than descending into the scrotum).Boys who don't have the condition corrected by the age of 11 are more likely to develop testicular cancer later. Other risk factors include having a brother or father who had testicular cancer, fertility problems, being from a wealthier social group, being white or having a rare complication of mumps called orchitis(painful swelling of the testicles).
Attribution: BUPA