What is testicular cancer?
Testicular cancer starts in the cells of the testicle. A cancerous (malignant) tumour is a group of cancer cells that can grow into nearby tissue and destroy it. The tumour can also spread (metastasize) to other parts of the body.
The testicles are part of the male reproductive system. These 2 egg-shaped organs are covered by a sac of skin called the scrotum. The scrotum hangs below the penis, between the legs. Each testicle is held in the scrotum by a spermatic cord, which is a bundle of nerves, lymph vessels and blood vessels leading to and from the testicles. The spermatic cord also contains part of the duct that moves sperm from the testicle to the urethra (called the vas deferens).
The testicles make sperm. They also make a male sex hormone called testosterone.
The testicles may also be called the testes (singular “testis”).
Cells in the testicle sometimes change and no longer grow or behave normally. These changes may lead to non-cancerous (benign) conditions such as epididymitis, orchitis and hydrocele. They can also lead to non-cancerous tumours such as some forms of benign sex cord stromal tumours.
Changes to cells of a testicle can also cause precancerous conditions. This means that the abnormal cells are not yet cancer, but there is a chance that they may become cancer if they aren’t treated. The most common precancerous condition of the testicle is germ cell neoplasia in situ (GCNIS).
But in some cases, changes to testicle cells can cause cancer. Most often, testicular cancer starts in germ cells. These cells make sperm. These types of tumours are called germ cell tumours. The 2 main types of germ cell tumours that develop in the testicles are seminomas and non-seminomas.
Rare types of testicular cancer can also develop. These include cancerous sex cord stromal tumours and non-Hodgkin lymphoma of the testis.
Structure of the testicles
Each testicle is covered by tough, fibrous layers of tissue called the tunica. The outer layer is called the tunica vaginalis and the inner layer is called the tunica albuginea.
The testicle is divided into parts called lobules. Each lobule contains tiny U-shaped tubes called seminiferous tubules. There are about 800 seminiferous tubules tightly coiled within each testicle.
The seminiferous tubules open into a series of uncoiled, interconnected channels called the rete testis. Ducts, or tubes, connect the rete testis to a tightly coiled tube called the epididymis. The epididymis joins to a long, large duct called the vas deferens.
Each testicle is held in the scrotum by a spermatic cord. Each spermatic cord is made of tough connective tissue and muscle. It contains nerves, lymph vessels, blood vessels and part of the vas deferens.
What the testicles do
The testicles make sperm and sex hormones. The 2 main types of cells in the testicles that perform these functions are germ cells and stromal cells.
Germ cells line the seminiferous tubules. They mature into sperm cells as they move from the lining through the seminiferous tubules and into the epididymis. The epididymis stores sperm cells and helps them completely mature.
Stromal cells help other cells in the testicle. Different types of stromal cells do different things:
- Sertoli (nurse) cells are a type of stromal cell found in the seminiferous tubules. They support the germ cells by helping make and transport sperm.
- Leydig cells are a type of specialized stromal cell found in the space between the seminiferous tubules. They make testosterone. Testosterone helps germ cells make sperm.
Testosterone also helps the reproductive organs develop and function. It gives men their:
- sex drive (libido)
- fully developed genitals
- deep voice
- body and facial hair
- bigger muscles and body size
Cancerous tumours of the testicle
Precancerous condition of the testicle
Non-cancerous tumours and conditions of the testicle
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