Immunotherapy is treatment that uses certain parts of a persons immune system to fight diseases such as cancer. This can be done in a couple of ways. For a long time doctors suspected that the immune system could affect certain cancers. In the late 1800s, he began treating cancer patients by infecting them with certain kinds of bacteria, which came to be known as Coley toxins. Although he had some success, his technique was overshadowed when other forms of cancer treatment, such as radiation therapy, came into use. Since then, doctors have learned a great deal about the immune system and how it might be used to treat cancer. In the last few decades immunotherapy has become an important part of treating some types of cancer. Newer types of immune treatments are now being studied for many other types, and theyll impact how we treat cancer in the future.