Oncology (Treatment of Cancer)
Oncology is the branch of medicine that studies cancers to understand their development, diagnosis, treatment, and prevention. A medical professional who practices oncology is an oncologist. The term originates from the Greek onkos, meaning bulk, mass, or tumor and the suffix ology, meaning study of. The oncologist often coordinates the multi-disciplinary care of cancer patients, which may involve physiotherapy, counseling, clinical genetics, and others disciplines. Also, the oncologist often must liaise with pathologists on the exact biological nature of the tumor that is being treated.
Oncology is concerned with:
- The diagnosis of cancer
- Therapy (e.g. surgery, chemotherapy, radiotherapy and other modalities)
- Follow-up of cancer patients after successful treatment
- Palliative care of patients with terminal malignancies
- 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).
The most important diagnostic tool in oncology, as in the rest of medicine, remains the medical history: the character of the complaints and any specific symptoms (fatigue, weight loss, unexplained anemia, fever of unknown origin, and other phenomena and signs). The physical examination may reveal the location of a malignancy. Other diagnostic methods include:
- Biopsy, either incisional or excisional;
- Endoscopy, either upper or lower gastrointestinal, bronchoscopy, or nasendoscopy;
- X-rays, CT scanning, MRI scanning, ultrasound and other radiological techniques;
- Single Photon Emission Computed Tomography
- Blood tests, including Tumor markers, which can increase the suspicion of certain types of tumors or even be pathognomonic of a particular disease.
Apart from in diagnosis, these modalities (especially imaging by CT scanning) are often used to determine whether the tumor can be surgically removed in its entirety. A tissue diagnosis from a biopsy is considered essential for the proper identification of cancer. When this is not possible, empirical therapy, without an exact diagnosis, may be given, based on the available evidence. Occasionally, a metastatic lump or pathological lymph node is found (typically in the neck) for which a primary tumor cannot be found. This situation is referred to as “carcinoma of unknown primary,” and treatment is empirical based on past experience of the most likely origin.
Therapy completely on the nature of the tumor identified. Certain disorders will require immediate admission and chemotherapy (such as ALL or AML), while others can be followed up with regular physical examination and blood tests. Surgery may be attempted to remove a tumor entirely. When it is certain that cancer will remain, curative surgery is often impossible. This is so, for example, when there are metastases elsewhere, or when the tumor has invaded a structure that cannot be operated upon without risking the patient’s life. Occasionally surgery can improve survival even if not all tumor tissue has been removed. This is referred to as “debulking,” i.e. reducing the overall amount of tumor tissue. Surgery is also used for the palliative treatment of some of cancers, e.g. to relieve biliary obstruction, or to relieve the problems associated with some cerebral tumors. The risks of surgery must be weighed up against the benefits.
Chemotherapy and radiotherapy are used as a first-line radical therapy in a number of malignancies. They are also used for adjuvant therapy when the macroscopic tumor has already been completely removed surgically but there is a reasonable statistical risk that it will recur. Chemotherapy and radiotherapy are commonly used for palliation, where disease is clearly incurable. The aim is to improve the quality of life and to prolong life. Hormone therapy is used, particularly in the treatment of breast and prostate cancer. There is currently a rapid expansion in the use of monoclonal antibody treatments, notably for lymphoma, and breast cancer. Vaccine and other immunotherapies are the subject of intensive research. The application of ultrasound therapy for solid tumors is under investigation.