Definition of Testicular cancer:

Testicular cancer is cancer that starts in the testicles, the male sex glands located next to the penis.

Causes, incidence, and risk factors:

The exact cause of testicular cancer is unknown. However, several factors seem to increase a man's risk for the condition. They include:

• Abnormal testicle development
• History of undescended testicle(s)
• History of testicular cancer
• Klinefelter syndrome

Other factors under investigation as possible causes include exposure to certain chemicals and HIV infection. A family history of testicular cancer may also increase risk.

There is no link between vasectomy and testicular cancer.

Testicular cancer accounts for only 1% of all cancers in men in the U.S., but is the most common form of cancer in men age 15 - 40. In rare cases, it may occur at a younger age.

White men are five times more likely to develop this type of cancer than African Americans. White men are twice as likely as Asian-American men to have testicular cancer.

There are two main types of testicular cancer: Seminomas and nonseminomas. These cancers grow from germ cells, the cells that make sperm.

Seminoma: This is a slow-growing form of testicular cancer usually found in men in their 30s and 40s. The cancer is usually just in the testes. However, it can spread to the lymph nodes.

Nonseminoma: This more common type of testicular cancer tends to grow more quickly than seminomas. Nonseminoma tumors are often made up of different cell types, and are identified according to the cells in which they start to grow. Nonseminoma testicular cancers include:

• Choriocarcinoma (rare)
• Embryonal carcinoma
• Teratoma
• Yolk sac tumor

A stromal tumor is a rare type of testicular tumor. Such tumors are usually not cancerous. The two main types of stromal tumors are Leydig cell tumors and Sertoli cell tumors. Leydig cells release the hormone testosterone, and Sertoli cells are where sperm matures. Stromal tumors may be seen during childhood.