Testis, cancer of

A rare, cancerous tumour of the testis. Testicular cancer is most common in young to middle-aged men, and the risk increases in individuals with a history of undescended testis (see testis, undescended). The most common types of testicular cancer are seminomas, which are made up of only 1 type of cell, and teratomas. The cancer usually appears as a firm, painless swelling of 1 testis. There may also be pain and inflammation. Biopsy, followed by orchidectomy, is the usual treatment, and may be combined with chemotherapy. The tumours usually respond well to treatment.