Testicular cancer is a disease that occurs when abnormal cells in the testicles (testes) begin to grow in an uncontrolled manner. Although rare, it is the most common form of cancer in men ages 20 to 35 and is among the most curable types of cancer, especially when it is detected at an early stage.

The testes are the two male sex organs, or gonads, that produce and store sperm. The testes also produce testosterone, a male hormone. The testes are located in a pouch below the penis called the scrotum.

Common symptoms of testicular cancer include an often painless change in the size or shape of one or both testes, a feeling of heaviness in the scrotum, or a dull pain in the lower back, abdomen, or groin.

Testicular cancer is most common among white males and is considered uncommon in men of African and Asian descent.