Cancer has been around for many thousands of years. Today, a lot of the medical terms used to describe cancer come from ancient Greek and Latin. For example, the Latinized Greek word carcinoma is used to describe a malignant tumor - a tumor made up of cancer cells. The Greeks also used the word "karkinos", which would be translated by Aulus Cornelius Celsus into the Latin word "cancer". The prefix 'carcino' is still used in medical words like carcinoma and carcinogenic. A famous Greek doctor, Galen, helped create another word that is very important to medicine today by using the word ""onkos"" to describe "all" tumours. This is where the word oncology, the branch of medicine that deals with cancer, comes from.