Oncology is the branch of medicine that researches, identifies, and treats cancer. A physician who works in the field of oncology is an oncologist.

Oncologists must first diagnose 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.

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 at multi-disciplinary cancer conferences where medical oncologists, surgical oncologists, radiation oncologists, 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 the management of cancer are quite common.