Oncology is the branch of medicine that deals with the diagnosis and treatment of cancer. Thus it is a disease specific branch not an organ specific branch. The common treatment of cancer includes surgery, chemotherapy, radiations and targeted therapies. However in cases like skin you may have immunotherapy, kidney may have multi-kinase inhibitors etc. This specialisation is divided into 3 divisions Medical oncology, Surgical oncology and Radiation oncology besides there are multiple sub specialities in oncology.