An oncologist is a doctor who specializes in the diagnosis and treatment of cancer. They provide medical care for people diagnosed with cancer and often act as the main healthcare provider for someone with cancer, designing treatment plans, offering supportive care, and sometimes coordinating treatment with other specialists. Oncology is the study of cancer, and the field of oncology has three major areas based on treatments: medical oncology, radiation oncology, and surgical oncology. Medical oncologists treat cancer using medication, including chemotherapy, immunotherapy, and targeted therapy. Radiation oncologists treat cancer using radiation therapy, which is the use of high-energy x-rays or other particles to destroy cancer cells. Surgical oncologists treat cancer using surgery, including removing the tumor and nearby tissue during an operation. This type of surgeon can also perform certain types of biopsies to help diagnose cancer. There are also medical terms for oncologists who specialize in caring for specific groups of patients or groups of cancers, such as geriatric oncologists, gynecologic oncologists, hematologist-oncologists, and neuro-oncologists. Oncologists can diagnose cancer, identify treatment options, and discuss each options benefits and side effects. They oversee the course of treatment and manage post-treatment care.