The term oncology literally means a branch of science that deals with tumours and cancers. The word “onco” means bulk, mass, or tumor while “-logy” means study.
Each of the cells of the body have a tightly regulated system that controls their growth, maturity, reproduction and eventual death. Cancer begins when cells in a part of the body start to grow out of control. There are many kinds of cancer, but they all start because of out-of-control growth of abnormal cells.
Today, millions of people are living with cancer or have had cancer. Cancer is the second leading cause of death in the United States. About one-half of all men and one-third of all women in the US will develop cancer during their lifetimes.
Some of the earliest evidence of cancer is found among fossilized bone tumors, human mummies in ancient Egypt, and ancient manuscripts. Abnormalities suggestive of the bone cancer called osteosarcoma have been seen in mummies.
Among manuscripts the first known description of cancer is seen in the Edwin Smith Papyrus and is a copy of part of an ancient Egyptian textbook on trauma surgery. It describes 8 cases of tumors or ulcers of the breast that were treated by cauterization with a tool called the fire drill. It dates back to about 3000 BC. The papyrus describes the condition as “incurable”.
Medical professionals who practice oncology are called Cancer specialists or oncologists. These oncologists have several specific roles. They help in diagnosis of the cancer, help in staging the cancer and grading the aggressive nature of the cancer.
The most important diagnostic tool remains the clinical history of the patient. Common symptoms that point towards cancer include fatigue, weight loss, unexplained anemia, fever of unknown origin etc.
Oncology depends on diagnostic tools like biopsy or removal of bits of the tumour tissue and examining it under the microscope. Other diagnostic tools include endoscopy for the gastrointestinal tract, imaging studies like X-rays, CT scanning, MRI scanning, ultrasound and other radiological techniques, Scintigraphy, Single Photon Emission Computed Tomography, Positron emission tomography and nuclear medicine techniques etc.
Common methods include blood tests for biological or tumor markers. Rise of these markers in blood may be indicative of the cancer.
Based on the grade and stage of the cancer, oncologists help plan the therapy that is suitable for each of their patients. This could be by surgery, chemotherapy, radiation therapy and other modalities.
Treatment of cancer may involve other specialists as well. This includes a surgeon, a radiation oncologists or a radiotherapist etc. the whole of the cancer therapy however is co-ordinated by the oncologists.
Once initial therapy is completed the oncologists is responsible for follow up of the patient to detect relapse and remission. The former means recurrence or return of the cancer while being in remission means remaining cancer-free.
The oncologist is also responsible for palliative or symptomatic care in patients with terminal malignancies. This and other issues of treatment choice have several ethical issues including patient autonomy and choice that the oncologist needs to be concerned about.
Oncology and cancer research involves screening the general population for cancer and screening the relatives of patients (in types of cancer that are thought to have a hereditary basis. For example, in breast cancer both population screening by regular mammography and familial screening by genetic analysis of the BRCA1 and BRCA2 genes is performed.
There is a tremendous amount of research being conducted on all areas of oncology, ranging from cancer cell biology to chemotherapy treatment regimens and optimal palliative care and pain relief. This makes oncology a continuously changing and developing field.
Cancer research is carried out in clinical trials. In the UK, patients are often enrolled in large studies coordinated by Cancer Research UK (CRUK), Medical Research Council (MRC), the European Organisation for Research and Treatment of Cancer (EORTC) or the National Cancer Research Network (NCRN).
Cancers are often considered incurable. With advances in diagnostic methods that allow early diagnosis and detection of cancer and advances in therapeutic modalities there are innumerable patients living fruitful lives with cancer.
People who have been successful in keeping their cancer away with treatment are said to be in remission. However, even after successful therapy and years of remission there remains a risk of relapse and return of cancer. Cancer patients thus need appropriate therapy and follow up to detect the reappearance of the cancer.
Therapy of cancers depends on many factors. Some of these are:
Cancer therapies include surgery, radiation therapy and chemotherapy.
The primary and oldest treatment for cancer is surgery, and several special surgical techniques can be used. Surgery is used also in diagnosis and staging to determine the extent and amount of disease.
Surgical therapy may be of two types - prophylactic surgery and therapeutic or curative surgery. The patient may elect for prophylactic surgery that involves removal of tissue that is not malignant but which may become malignant. A common example is prophylactic or precautionary removal of the breasts in women with a mutation in the BRCA gene that raises their risk of getting breast cancer.
Curative surgery involves removal of the tumor and is often done in conjunction with chemotherapy or radiotherapy to achieve a cure.
There is another type of surgery called palliative surgery. Palliative surgery is not done to cure cancer but is used to treat complications of advanced disease. This type of surgery may also be used to remove the bulk of the tumor.
For example, palliative surgery can debulk tumors that are blocking the function of organs. Palliative surgery is also used to treat pain that is difficult to control in other ways like medications.
Radiotherapy uses radiation to kill cells. All cells of the body have a cell cycle. The cell grows from G0, G1, S, G2, and M.
Radiation is most effective on cells in the dividing stages and less effective on cells in the “resting” phase of G0. Radiation therapy aims to stop cancer cells from dividing, thus killing them and destroying the tumor.
Radiation therapy, however, is not selective and may affect the rapidly dividing surrounding healthy cells as well. This includes cells that line the mouth and hair cells, are often destroyed also, leading to mucositis (sores in the mouth or mouth ulcers) and alopecia (loss of hair), respectively.
Other dividing cells such as blood cells are also destroyed in the process of radiation leading to low White blood cell counts and a susceptibility to infections and a low Red blood cell count leading to anemia. There may also be a low platelet count leading to bleeding tendencies.
Radiotherapy is a gradual process, with the total dose measured in grays given over an extended period of time. Very often, patients receive radiotherapy every week day for 6 weeks. The weekend is allowed for normal cells to recover. This time also allows the dead cancer cells to be removed from the body. Radiotherapy often incorporates drugs or medications such as radioprotectors or radiosensitizers to lessen damage to healthy tissue and improve the outcomes.
Radiation may be given using external beam radiation that involves visits to the doctor’s office each day of the week for the radiation dose. Hyperfractionated radiotherapy delivers radiation in smaller doses administered every 4 to 6 hours, 2 or 3 times a day. This is useful for rapidly dividing tumors.
Another form of radiotherapy is internal radiation, in which an implanted radioactive material is used to deliver a continuous dose of radiation over several days. Internal radiation is also termed brachytherapy.
Chemotherapy is the administration of drugs to kill cancer cells. Chemotherapeutic drugs can be administered as a pill, as an injection, or as an intravenous infusion. There are several hundreds of chemotherapeutic drugs that are being used alone or in combination, to treat cancer.
Like radiotherapy, chemotherapy targets rapidly dividing cells, usually aiming to disrupt cell division. Chemotherapy may be used after surgery or radiation to kill off the remaining cancer cells that have been missed by the other modalities of therapy.
Various forms of chemotherapy exist and most are categorized as antineoplastic or anticancer therapy. Many types of drugs are used as antineoplastic therapy, including alkylating agents, antimetabolites, and enzyme inhibitors.
Chemotherapy is generally given as 3 stages:
The number of cycles in each course can vary. Chemotherapy is given in cycles, with a rest period between cycles, and cycles can last from 3 months to 3 years, depending on a number of factors. Cancer chemotherapy duration depends on type of cancer, type of drugs and responses like tumor shrinkage or progression. Chemotherapy is further classified as adjuvant or neoadjuvant, if given after or before surgery, respectively.
There are several new approaches in chemotherapy as well:
If detected early, many cancers can be treated effectively. Around 50% of the cancers can be cured with radical treatment. For pediatric patients, that number is much higher. Despite this, a large number of cancer patients die each year from the disease and its complications.
According to the World Health Organization (WHO) in 2002, “Palliative care is an approach that improves the quality of life of patients and their families facing the problems associated with life-threatening illness, through the prevention and relief of suffering by means of early identiﬁcation and impeccable assessment, and treatment of pain and other problems – physical, psychosocial and spiritual.”
Palliative care refers to the symptom relief that is provided to patients at the terminal stages of their cancer. Palliative care provides symptom relief for the patient and also psychosocial and supportive care for the patient and his or her family members. Palliative care is useful in patients who are in advanced stages of cancer and have a very low chance of being cured, or when they are facing the terminal phase of the disease.
These end phases of cancer are often burdened with need for emotional, spiritual, social and economic support. Palliative care is an urgent humanitarian need worldwide for people with cancer and other chronic fatal diseases especially at end stages.
Ideally palliative care services should be provided from the time of diagnosis of life-threatening illness and the services should continue throughout the course of the disease.
Palliative care services also include bereavement support for the family. To be effective, these services need to be integrated into the existing health system at all levels of care, especially community and home-based care. These need involvement of both public and the private sector and need to adapt to the speciﬁc cultural, social and economic setting of the community. Palliative care is an essential part of the multidisciplinary cancer care team.