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.[1] The name's etymological origin is the Greek word ὄγκος (ónkos), meaning "tumor", "volume" or "mass".[2] Oncology is concerned with:
The diagnosis of any cancer in a person (pathology)
of the relatives of patients (in types of cancer that are thought to have a hereditary basis, such as breast cancer)
Diagnosis
Medical histories remain an important screening tool: the character of the complaints and nonspecific symptoms (such as fatigue, weight loss,[3] unexplained anemia,[4]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)[5]
Endoscopy, either upper or lower gastrointestinal, cystoscopy, bronchoscopy, or nasendoscopy; to localise areas suspicious for malignancy and biopsy when necessary.[6]
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 empirically based on past experience of the most likely origin.[7]
Therapy
Depending upon the cancer identified, follow-up and palliative care will be administered at that time. Certain disorders (such as ALL or AML) will require immediate admission and chemotherapy, 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, 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 cancers, e.g. to relieve biliary obstruction, or to relieve the problems associated with some cerebral tumors. The risks of surgery must be weighed against the benefits.
Chemotherapy and radiotherapy are used as a first-line radical therapy in several 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 life and to prolong it.
Hormone manipulation is well established, particularly in the treatment of breast and prostate cancer.
Approximately 50% of all cancer cases in the Western world can be treated to remission 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 specialty 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 issues
There are a number of recurring ethical questions and dilemmas in oncological practice. These include:
What information to give the patient regarding disease extent/progression/prognosis.
These issues are closely related to the patient's personality, religion, culture, and family life. Though these issues are complex and emotional, the answers are often achieved by the patient seeking counsel from trusted personal friends and advisors. 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
There is a tremendous amount of research being conducted on all frontiers of oncology, ranging from cancer cell biology, and radiation therapy to chemotherapy treatment regimens and optimal palliative care and pain relief. Next-generation sequencing and whole-genome sequencing have completely changed the understanding of cancers. Identification of novel genetic/molecular markers will change the methods of diagnosis and treatment, paving the way for personalized medicine.
^ ab"Types of Oncologists". Cancer.Net : American Society of Clinical Oncology (ASCO). 2011-05-09. Archived from the original on 2013-06-01. Retrieved 25 May 2013.
^Manganaris, Argyris; Black, Myles; Balfour, Alistair; Hartley, Christopher; Jeannon, Jean-Pierre; Simo, Ricard (2009-07-01). "Sub-specialty training in head and neck surgical oncology in the European Union". European Archives of Oto-Rhino-Laryngology. 266 (7): 1005–1010. doi:10.1007/s00405-008-0832-4. ISSN1434-4726. PMID19015865. S2CID20700214.
^Shaw, Peter H.; Reed, Damon R.; Yeager, Nicholas; Zebrack, Bradley; Castellino, Sharon M.; Bleyer, Archie (April 2015). "Adolescent and Young Adult (AYA) Oncology in the United States: A Specialty in Its Late Adolescence". Journal of Pediatric Hematology/Oncology. 37 (3): 161–169. doi:10.1097/MPH.0000000000000318. ISSN1536-3678. PMID25757020. S2CID27695404.
