 Cancer has been around for thousands of years, but it wasn't until the late 19th century that treatments became more effective. In the early 20th century, the discovery of x-rays led to the development of chemotherapy, which has since become the mainstay of cancer treatment. Since then, research into targeted therapies and immunotherapies has greatly improved outcomes for many types of cancer. This article was authored by Luca Falzone, Salvatore Salimoni, Salvatore Salimoni, and others.