Testicular cancer is a malignant tumour that starts in cells of a testicle. Malignant means that it can spread, or metastasize, to other parts of the body.
The testicles are part of a man’s reproductive system. They are 2 egg-shaped organs that hang below the penis in a pouch of loose skin called the scrotum. The spermatic cord runs from the abdomen down to each testicle. It contains the vas deferens, some lymph nodes, veins and nerves. The testicles make the male sex hormone testosterone. They also make sperm.
Cells in a testicle sometimes change and no longer grow or behave normally. These changes may lead to non-cancerous, or benign, conditions such as orchitis, epididymitis or hydrocele. They can also lead to non-cancerous tumours such as benign germinal tumours and benign gonadal stromal tumours.
Changes to cells in a testicle can also cause precancerous conditions. This means that the cells are not yet cancer but there is a higher chance these abnormal changes will become cancer. The most common precancerous condition of the testicle is intratubular germ cell neoplasia (ITGCN).
In some cases, changes to testicle cells can cause cancer. More than 90% of all testicular cancers start from germ cells. Germ cells are the cells that become sperm in the testicles. These tumours are called germ cell tumours. The 2 types of germ cell tumours are seminomas and non-seminomas.
Rare types of testicular cancer can also develop. These include sex cord, or gonadal, stromal tumours and non-Hodgkin lymphoma of the testis.