oncology n : the branch of medicine concerned with the study and treatment of tumors
EtymologyFirst attested 1857, from onco- "tumor," from onkos "lump, mass, bulk" + -logy "study of," from Gr. logia, from logos, "word."
Oncology is the branch of medicine that studies tumors (cancer) and seeks to understand their development, diagnosis, treatment, and prevention. A medical professional who practices oncology is an oncologist. The term originates from the Greek onkos (ογκος), meaning bulk, mass, or tumor and the suffix -ology, meaning "study of".
The oncologist often coordinates the multidisciplinary care of cancer patients, which may involve physiotherapy, counselling, clinical genetics, to name but a few. On the other hand, the oncologist often has to 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
- Ethical questions surrounding cancer care
- of populations, or
- of the relatives of patients (in types of cancer that are thought to have a hereditary basis, such as breast cancer).
DiagnosisThe most important diagnostic tool remains the medical history: the character of the complaints and any specific symptoms (fatigue, weight loss, unexplained anemia, fever of unknown origin, paraneoplastic phenomena and other signs). Often a physical examination will reveal the location of a malignancy.
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;
- Scintigraphy, Single Photon Emission Computed Tomography, Positron emission tomography and other methods of nuclear medicine;
- 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 operability, i.e. whether it is surgically possible to remove a tumor in its entirety.
Generally, 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 (e.g. history, x-rays and scans.)
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 again, treatment is empirical based on past experience of the most likely origin.
TherapyIt depends completely on the nature of the tumor identified what kind of therapeutical intervention will be necessary. Certain disorders will require immediate admission and chemotherapy (such as ALL or AML), while others will be followed up with regular physical examination and blood tests.
Often, surgery is attempted to remove a tumor entirely. This is only feasible when there is some degree of certainty that the tumor can in fact be removed. When it is certain that parts will remain, curative surgery is often impossible, e.g. 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 tumour tissue has been removed; the procedure is referred to as "debulking" (i.e. reducing the overall amount of tumour 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 tumours. 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, i.e. 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: in this situation the aim is to improve the quality of and prolong life.
Hormone manipulation is well established, 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 (Rituximab), and breast cancer (Trastuzumab).
The application of ultrasound in the form of HIFU to solid tumors is under investigation.
Follow-upA large segment of the oncologist's workload is the following-up of cancer patients who have been successfully treated. For some cancers, early identification of recurrence, with prompt treatment, can lead to better survival and quality of life. It depends on the nature of the cancer whether the follow-up lasts a number of years or remains "life long".
Palliative careApproximately 50% of all cancer cases in the Western world can be cured with radical treatment. For pediatric patients, that number is much higher. A large number of cancer patients will die from the disease, and a significant proportion of patients with incurable cancer will die of other causes. There may be ongoing issues with symptom control associated with progressive cancer, and also with the treatment of the disease. These problems may include pain, nausea, anorexia, fatigue, immobility, and depression. Not all issues are strictly physical: personal dignity may be affected. Moral and spiritual issues are also important.
While many of these problems fall within the remit of the oncologist, palliative care has matured into a separate, closely allied speciality to address the problems associated with advanced disease. Palliative care is an essential part of the multidisciplinary cancer care team. Palliative care services may be less hospital-based than oncology, with nurses and doctors who are able to visit the patient at home.
Ethical issuesThere are a number of recurring ethical questions and dilemmas in oncological practice. These include:
These issues are closely related to the patients' personality, religion, culture, personal, and family life. The answers are rarely black and white. It requires a degree of sensitivity and very good communication on the part of the oncology team to address these problems properly.
Progress and research in oncologyThere is a tremendous amount of research being conducted on all frontiers of oncology, ranging from cancer cell biology to chemotherapy treatment regimens and optimal palliative care and pain relief. This makes oncology a continuously changing field.
Therapeutic trials often involve patients from many different hospitals in a particular region. In the UK, patients are often enrolled in large studies coordinated by Cancer Research UK (CRUK, http://www.cancerresearchuk.org.uk), Medical Research Council (MRC, http://www.mrc.ac.uk), the European Organisation for Research and Treatment of Cancer (EORTC, http://www.eortc.be) or the National Cancer Research Network (NCRN, http://www.ncrn.org.uk).
Complementary and alternative therapies
Many cancer patients seek extra help from complementary and alternative therapies, which fall outside of conventional medicine. Most complementary therapies do not have a firm scientific or evidence base. Some patients undoubtedly find complementary therapies helpful while they are undergoing conventional treatment.
While most complementary therapies are probably harmless, they can be expensive. They may also be positively harmful if the patient forgoes conventional treatment altogether, in order to follow alternative regimens. Some alternative regimens are undoubtedly hazardous.
SpecialitiesThere are several subspecialties within oncology. Moreover, oncologists often develop an interest and expertise in the management of particular types of cancer.
Oncologists may be divided on the basis of the type of treatment provided.
- Radiation oncology: treatment primarily with radiation, a process called radiotherapy.
- Surgical oncology: surgeons who specialize in tumor removal.
- In the United Kingdom and several other countries, oncologists may be either clinical or medical oncologists. The main difference is that clinical oncologists deliver radiotherapy, while medical oncologists do not. (This difference does not apply in North America: the terms, clinical oncologist and medical oncologist are used interchangeably.)
Gynecologic oncology focuses on cancers of the female reproductive system.
In veterinary medicine, veterinary oncology is the subspecialty that deals with cancer diagnosis and treatment in animals.
- Vickers, A., Banks, J., et al. Alternative Cancer Cures: "Unproven" or "Disproven"? CA Cancer J Clin 2004 54: 110-118. Full text online
- National Cancer Institute
- American Cancer Society
- PACT: Programme of Action for Cancer Therapy Program to establish cancer care capacity and comprehensive cancer control in developing world
- Canadian Cancer Society
- BC Cancer Agency
- International Agency for Research on Cancer
- Cancer Research UK
- MacMillan cancer relief
- Multinational Association of Supportive Care in Cancer
- Quackwatch guide to alternative cancer therapies
- Oncowiki: A Wiki based repository of Cancer Chemotherapy Regimens
- [http://www.asco.org: American Society of Clinical Oncology]
- [http://www.plwc.org: People Living With Cancer]
- [http://www.plwc.org.za: People Living With Cancer South Africa]
- Articles on the scientific basis of popular alternatives.
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