Testicular cancer is the most common form of cancer in males between the ages of 15 and 35. However, it accounts for only 1 percent of all cancers in men. An estimated 8,090 men will be diagnosed with testicular cancer in 2008, according to the American Cancer Society.
The testicles are the male reproductive organs that produce sperm and male hormones. Sperm is produced by adult males as an essential part of reproduction. Male hormones control the development of the reproductive organs, as well as other male characteristics, such as body and facial hair, deep voice, and wide shoulders. The testicles, which are also called testes, are located behind the penis in a pouch of skin called the scrotum.
Cancer that develops within one or both testicles is called testicular cancer. It is one of the most curable forms of cancer. Other names for cancer of the testicles are cancer of the testes, testes cancer, or testis cancer. (The plural of "testis" is "testes." Most men have one testis on each side, or two testes total.)
The exact cause of testicular cancer is not known. One of the major risk factors for testicular cancer is cryptorchidism, a condition in which one or both of the testicles have not descended into the scrotum. Normally, testicular descent occurs before birth. Other risk factors include Kleinfelter's syndrome (an inherited disorder), a family history of testicular cancer, infection with the human immunodeficiency virus (HIV), and exposure before birth to the hormone diethylstilbestrol (DES), which in the past was sometimes prescribed to pregnant women.