What Is It?

Testicular cancer is the uncontrolled growth of abnormal cells in one or both testicles, also called testes. The testicles are the male sex glands that are located behind the penis in the scrotum. They produce testosterone and other male hormones. They also produce and store sperm, the male reproductive cells.

Different types of testicular cancer start in different cells in the testicles:

• Germ cell tumors - About 95% of testicular cancers develop in germ cells, cells that form sperm. There are two types of germ cell tumors. Seminomas (40% of all testicular cancers) tend to grow slowly, and also tend to stay within the testicles for a long period without spreading. Nonseminomas form in more mature germ cells and are more likely to spread aggressively, especially to lymph nodes (bean-shaped structures throughout the body that produce and store infection-fighting cells).

• Tumors of supportive tissues - About 5% of testicular cancers begin in the testicles' supporting tissues, tissue that does not produce sperm. These cancers are called Sertoli-cell tumors and Leydig-cell tumors.

Once testicular cancer develops, it can remain within the testicle, or it can spread to lymph nodes in the abdomen. If it remains undetected, testicular cancer eventually can spread to the lungs, brain, liver and elsewhere throughout the body.

Testicular cancer is uncommon. It accounts for only 1% of all cancers in men in the United States, and it strikes only two to three of every 100,000 American males each year. Testicular cancer can affect men of any age, but it is most common in men between the ages of 20 and 40. It occurs eight times more often in white men than in black men. Although the specific cause of testicular cancer is not known, the illness is more common in men who had an undescended testicle at birth. Roughly 10% of cases of testicular cancer occur in men who have had an undescended testicle, and one quarter of these cases occur in the testicle that descended normally. Testicular cancer also appears more commonly in men with certain genetic conditions, such as Klinefelter syndrome or Down syndrome; men who have a family history of testicular cancer; and possibly men with HIV infection.

Symptoms

The most common symptom of testicular cancer is a painless lump in the testicle. This lump can be small or large, and can be hard or soft. Some men also will have discomfort or swelling in the testicle that can mimic an infection. Breast swelling or tenderness also can occur. If cancer has spread beyond the testicle, there can be a variety of symptoms, including back or abdominal pain and shortness of breath.