Illustration of the location of the testicles
The testicles are two small, egg-shaped glands located below the penis in the sac of loose skin called the scrotum. Testicles contain germ cells, which produce sperm, and other specialized cells that make the male hormone testosterone.
Testicular cancer is a relatively rare disease that is diagnosed in approximately 8,500 men in the United States each year. While it accounts for only 1 percent of all cancers in men, it is the most common solid tumor diagnosed in those aged 15 to 35.
Types of Testicular Cancer
The vast majority – about 95 percent – of testicular cancers begin in germ cells, specialized cells in the testicles that make sperm. While most germ cell tumors begin in the testicles, this type of tumor can occasionally arise in the abdomen, chest, or other areas of the body, even if there is no evidence of cancer in or near the testicles.
Two main types of germ cell tumors can develop in the testicles: seminoma and nonseminoma tumors. About half of all germ cell tumors are seminomas, which are usually slow growing. Many early-stage seminomas can be cured because this type of tumor does not usually metastasize, or spread, to other areas of the body. Nonseminomas are often more aggressive than seminomas, and are more likely to metastasize beyond the testicle.
About 5 percent of testicular cancers begin in stromal cells, which produce the hormone testosterone. Stromal cell testicular tumors are not typically cancerous. A tumor in the testicle could also be a “secondary” cancer, in which a cancer from another part of the body has spread to the testicle. One example is lymphoma, which usually begins in lymph nodes elsewhere in the body.
There is no known connection between testicular cancer and any particular personal habit, activity, or lifestyle. However, your chance of developing testicular cancer may be greater if you have one of these risk factors:
- Undescended testicle (cryptorchidism): Normally, the testicles descend from inside the abdomen into the scrotum before birth. Males born with an undescended testicle have a greater risk of developing testicular cancer, even if they have corrective surgery.
- History of testicular cancer: Men who have had cancer in one testicle have a higher risk of developing a tumor in the other testicle.
Most men with testicular cancer complain of pain, swelling, or hardness in the testicles, or a combination of these symptoms. Any lump found in the testicle should be evaluated by a physician immediately.
Other, less common symptoms can include:
- a painless lump in the testicle
- heaviness in the scrotum
- ache in the lower abdomen or groin
- tenderness in the breast area due to high levels of a hormone called human chorionic gonadotropin (hCG)
- backache, due to enlargement of lymph nodes in more advanced testicular cancer
While these or other symptoms do not necessarily indicate cancer, early detection and treatment of testicular tumors greatly increases the chance of a cure.