The exact cause of testicular cancer is unknown. However, it occurs when healthy cells in the testicles develop changes in their DNA, leading to uncontrollable abnormal growth and the formation of a tumour which may be cancer (malignant).
Males who have a history of undescended testes (testes that did not descend to lie in the scrotum during development) have a much higher chance of developing testicular cancer. Other risk factors include history of testicular cancer in the other testis and family history of testicular cancer.
