Oncology, from Ancient Greek ὄγκος (ónkos), meaning "tumor, bulk", and λόγος (lógos), meaning "study", 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.
Oncology is focused on the diagnosis of cancer in a person, therapy (e.g., surgery, chemotherapy, radiotherapy and other modalities), monitoring of people after treatment, palliative care for people with advanced-stage cancers, ethical questions surrounding cancer care, screening of people who may have cancer, and the study of cancer treatments through clinical research.