Cancer, testicles: Testicular cancer is one of the most common cancers in younger men. The testicles produce the hormone testosterone and makes sperm. This type of cancer is most often found by men themselves as a lump in the testicle. The risk of cancer of the testicles is increased in males whose testicles did not descend into the scrotum (holding sac for the testicles) during fetal development. This condition is referred to as cryptorchidism or undescended testicles. When a growth in the testicle is detected, cancer is confirmed after surgical removal of the affected testicle (orchiectomy) and examination of the tissue under a microscope. Testicular cancer is almost always curable if it is found early. Modern chemotherapy can even cure the majority of those whose testicular cancers are found at more advanced stage, that is, that have spread elsewhere in the body.