Oncology is a branch of medicine that deals with the study, treatment, diagnosis, and prevention of cancer. A medical professional who practices oncology is an oncologist.

Cancer was first found in humans in the years 3000 BCE in Egypt. The Edwin Smith papyrus described a form of cancer as "a bulging tumor of the breast." Galen, a Greek doctor who lived from 130-200 CE, was the first to use the word onkos to describe tumors, from which the words "oncologist" and