Oncology is a branch of medicine that deals with the prevention, diagnosis, and treatment of cancer. A medical professional who practices oncology is an oncologist.

Cancer survival has improved due to three main components: improved prevention efforts to reduce exposure to risk factors (e.g., tobacco smoking and alcohol consumption), improved screening of several cancers (allowing for earlier diagnosis), and improvements in treatment.

Cancers are often managed through discussion on multi-disciplinary cancer conferences where medical oncologists, surgical oncologists, radiation oncologist, pathologists, radiologists, and organ specific oncologists meet to find the best possible management for an individual patient considering the physical, social, psychological, emotional, and financial status of the patient. It is very important for oncologists to keep updated with respect to the latest advancements in oncology, as changes in management of cancer are quite common.

Oncologists must first diagnose a cancer, which is usually carried out via biopsy, endoscopy, X-ray, CT scanning, MRI, PET scanning, ultrasound or other radiological methods. Nuclear medicine can also be used to diagnose cancer, as can blood tests or tumor markers. Oncology is often linked with hematology, which is the branch of medicine that deals with blood and blood-related disorders.

Once a diagnosis is made, the oncologist discusses disease stage with the patient. Staging will dictate treatment of the cancer. Chemotherapy — which is defined as the destruction of cancer cells — may be used, as well as radiation therapy. Surgery is used to remove tumors. Hormone therapy is used to treat certain types of cancers, and monoclonal antibody treatments are gaining popularity. Research into cancer vaccines and immunotherapies is ongoing. Palliative care in oncology treats pain and other symptoms of cancer.