It is a cancer of the sperm-producing cells of the testicle.

Cancer occurs when normal body cells get out of control, multiply and spread. These cells clump together to form a cancerous or malignant tumour which can then grow and damage healthy parts of the body.

There are two main types of testicular cancer:

Seminomas

These cancers are most likely to affect men aged between 20 and 50. They tend to grow more slowly and are less likely to spread to distant parts of the body. About one third of patients have this type of testicular cancer.

Non-seminomas

These are most likely to affect men aged between 18 and 35. They tend to grow more quickly and are more likely to spread. About two thirds of patients have this type of testicular cancer.