Oncology 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. The name’s etymological origin is the Greek word ὄγκος (ónkos), meaning “tumor”, “volume” or “mass”.
Oncology is concerned with:
- The diagnosis of any cancer in a person (pathology)
- Therapy (e.g. surgery, chemotherapy, radiotherapy and other modalities)
- Follow-up of cancer patients after successful treatment
- Palliative care of patients with terminal malignancies
- Ethical questions surrounding cancer care
- Screening efforts: of populations, or of the relatives of patients (in types of cancer that are thought to have a hereditary basis, such as breast cancer)
Medical histories remain an important screening tool: the character of the complaints and nonspecific symptoms (such as fatigue, weight loss, unexplained anemia, fever of unknown origin, paraneoplastic phenomena and other signs) may warrant further investigation for malignancy. Occasionally, a physical examination may find the location of a malignancy.
Diagnostic methods include:
- Biopsy or resection; these are methods by which suspicious neoplastic growths can be removed in part or in whole, and evaluated by a pathologist to determine malignancy. This is currently the gold standard for the diagnosis of cancer and is crucial in guiding the next step in management (active surveillance, surgery, radiation therapy, chemotherapy or a combination of these)
- Endoscopy, either upper or lower gastrointestinal, cystoscopy, bronchoscopy, or nasendoscopy; to localise areas suspicious for malignancy and biopsy when necessary.
- X-rays, CT scanning, MRI scanning, ultrasound and other radiological techniques to localise and guide biopsy.
- Scintigraphy, single photon emission computed tomography (SPECT), positron emission tomography (PET) and other methods of nuclear medicine to identify areas suspicious for malignancy.
- Blood tests, including tumor markers, which can increase the suspicion of certain types of cancers.
Apart from diagnoses, these modalities (especially imaging by CT scanning) are often used to determine operability, i.e. whether it is surgically possible to remove a tumor in its entirety.
Currently, a tissue diagnosis (from a biopsy) by a pathologist is essential for the proper classification of cancer and to guide the next step of treatment. On extremely rare instances when this is not possible, “empirical therapy” (without an exact diagnosis) may be considered, based on the available evidence (e.g. history, x-rays and scans.)
On very rare occasions, a metastatic lump or pathological lymph node is found (typically in the neck) for which a primary tumor cannot be found. However, immunohistochemical markers often give a strong indication of the primary malignancy. This situation is referred to as “malignancy of unknown primary”, and again, treatment is empirical based on past experience of the most likely origin.