Cancer begins when cells begin to develop out of control. Cells in almost any part of the body can grow cancer and expanded to other parts of the body. Cancer that begins in the testicles is called testicular cancer. A 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 majority 95% of testicular cancers are germ cell tumors. Treatment for testicular cancer is highly effective, with 5-year overall survival rates approaching 100% for localized disease.