Normal Anatomy and the Development of Testicular Cancer

The testicles (or testes) are a pair of male sex glands. They are located under the penis in a sac-like pouch called the scrotum. The testicles make hormones (androgens). Androgens control sexual development and sperm production. Immature sperm cells migrate through a network of tiny tubules called the epididymis. Sperm cells are stored and mature in this structure. During ejaculation, sperm cells move through the vas deferens, into the urethra, and out of the body.

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Cell division and cell are death normal. Changes in hormones can lead to changes in testicular cells and how they work. Signals in the cells that tell them when to grow and when to stop may get changed. Normally, the cells only grow enough to replace old or damaged cells. But damage may cause the abnormal growth of cells known as cancer.

Testicular cancer can start anywhere in the testicles. But the most common place is in the germ cells that make sperm. Testicular cancer can spread directly to nearby structures, then into the belly. The cancer can also spread to lymph nodes or blood vessels. When it does, it spreads to other parts of the body. The most common sites are to lymph nodes in other parts of the body and the lungs.

Types of Testicular Cancer

There are many types of testicular cancer. They're based on the cell type and where the cancer starts. The types are:

• Seminomas—Tend to grow more slowly than other types and are:
  • Classical—Make up over 95% of seminomas
  • Spermatocytic—Rare type that tends to occur in men over 60 years old
• Non-seminomas start in other cells in testicular tissue. They tend to grow faster and spread outside of the testicle more than seminomas. Non-seminomas are rare and are:
  • Embryonal
  • Yolk sac—Most common in infants and children
  • Choriocarcinoma
  • Teratoma

Some types of testicular cancers are a mix of different types of cells.