Etoposide (e-toe-POE-side) belongs to the group of medicines known as antineoplastic agents. It is used to treat cancer of the testicles and certain types of lung cancer. It is also sometimes used to treat some other kinds of cancer in both males and females. The exact way that etoposide acts against cancer is not known. However, it seems to interfere with the growth of the cancer cells, which are eventually destroyed.