Oncology is the branch of medicine concerned with the prevention, diagnosis and treatment of cancer. It is one of the most multidisciplinary areas of healthcare, drawing on surgery, radiology, pathology, radiotherapy, pharmacy, specialist nursing, palliative care and genomics, usually coordinated through a multidisciplinary team.
The field is conventionally divided into medical oncology, which deals with systemic anti-cancer therapy, clinical or radiation oncology, which delivers radiotherapy alongside systemic treatment, and surgical oncology. Haemato-oncology covers cancers of the blood and lymphatic system, and paediatric oncology is a distinct specialty with its own protocols.
Treatment decisions depend heavily on stage. The TNM system describes the size and local extent of the primary tumour (T), the involvement of regional lymph nodes (N) and the presence of distant metastases (M), which combine into an overall stage. Staging draws on imaging, pathology from biopsy or resection and, for some cancers, molecular profiling that identifies targetable mutations.
Modern oncology gives equal weight to what happens around treatment: early integration of palliative care, management of treatment toxicity, fertility preservation, psychological support, and structured survivorship care for the growing population living long term after a cancer diagnosis. Clinical trials are unusually central to the specialty, and access to them is often part of the treatment conversation itself.
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