TREATMENT OF CANCER

Cancer can be treated by surgery, chemotherapy:

radiation therapy, hormonal therapy, targeted therapy (including immunotherapy such as monoclonal antibody therapy) and synthetic lethality. The choice of therapy depends upon the location and grade of the tumour and the stage of the disease, as well as the general state of the patient (performance status). A number of experimental cancer treatments are also under development. Under current estimates, two in five people will have cancer at some point in their lifetime.

Complete removal of cancer without damage to the rest of the body (that is, achieving cure with near-zero adverse effects) is the ideal goal of treatment and is often the goal in practice. Sometimes this can be accomplished by surgery, but the propensity of cancers to invade adjacent tissue or to

Spread to distant sites by microscopic metastasis often limits its effectiveness, and chemotherapy and radiotherapy can have a negative effect on normal cells. Therefore, cure with no negligible adverse effects may be accepted as a practical goal in some cases; and besides curative intent, practical goals of therapy can also include suppressing cancer to a subclinical state and maintaining that state for years of good quality of life (that is, treating cancer as a chronic disease), and palliative care without curative intent (for advanced-stage metastatic cancers).
Because "cancer" refers to a class of diseases, it is unlikely that there will ever be a single "cure for cancer" any more than there will be a single treatment for all infectious diseases. Angiogenesis inhibitors were once thought to have potential as a "silver bullet" treatment applicable to many types of cancer, but this has not been the case in practice.

The treatment of cancer has undergone evolutionary changes as an understanding of the underlying biological processes has increased. Tumour removal surgeries have been documented in ancient Egypt, hormone therapy and radiation therapy were developed in the late 19th Century. Chemotherapy, immunotherapy and newer targeted therapies are products of the 20th century. As new information about the biology of cancer emerges, treatments will be developed and modified to increase effectiveness, precision, survivability, and quality of life.
In theory, non-haematological cancers can be cured if entirely removed by surgery, but this is not always possible. When cancer has metastasized to other sites in the body prior to surgery, complete surgical excision is usually impossible. In the Halsted a model of cancer progression, tumours grow locally, and then spread to the lymph nodes, then to the rest of the body. This has given rise to the popularity of local-only treatments such as surgery for small cancers. Even small localized tumours are increasingly recognized as possessing metastatic potential.
Examples of surgical procedures for cancer include mastectomy for breast cancer, prostatectomy for prostate cancer, and lung cancer surgery for non-small cell lung cancer. The goal of the surgery can be either the removal of only the tumour or the entire organ. A single cancer cell is invisible to the naked eye but can regroup into a new tumour, a process called recurrence. For this reason, the pathologist will examine the surgical specimen to determine if a margin of healthy tissue is present, thus decreasing the chance that microscopic cancer cells are left in the patient.

In addition to removal of the primary tumour, surgery is often necessary for staging, e.g. determining the extent of the disease and whether it has metastasized to regional lymph nodes. Staging is a major determinant of prognosis and of the need for adjuvant therapy. Occasionally, surgery is necessary to control symptoms, such as spinal cord compression or bowel obstruction. This is referred to as palliative treatment.
Surgery may be performed before or after other forms of treatment. Treatment before surgery is often described as neoadjuvant. In breast cancer, the survival rate of patients who receive neoadjuvant chemotherapy is no different to those who are treated following surgery. Giving chemotherapy earlier allows oncologists to evaluate the effectiveness of the therapy, and may make removal of the tumour easier. However, the survival advantages of neoadjuvant treatment in lung cancer are less clear.
Radiation therapy (also called radiotherapy, X-ray therapy, or irradiation) is the use of ionizing radiation to kill cancer cells and shrink tumours. Radiation therapy can be administered externally via external beam radiotherapy (EBRT) or internally via brachytherapy. The effects of radiation therapy are localized and confined to the region being treated. Radiation therapy injures or destroys cells in the area being treated (the "target tissue") by damaging their genetic material, making it impossible for these cells to continue to grow and divide. Although radiation damages both cancer cells and normal cells, most normal cells can recover from the effects of radiation and function properly. The goal of radiation therapy is to damage as many cancer cells as possible while limiting harm to nearby healthy tissue. Hence, it is given in many fractions, allowing healthy tissue to recover between fractions.

Radiation therapy may be used to treat almost every type of solid tumour, including cancers of the brain, breast, cervix, larynx, liver, lung, pancreas, prostate, skin, stomach, uterus, or soft tissue sarcomas. Radiation is also used to treat leukaemia and lymphoma. Radiation dose to each site depends on a number of factors, including the radio sensitivity of each cancer type and whether there are tissues and organs nearby that may be damaged by radiation. Thus, as with every form of treatment, radiation therapy is not without its side effects. Radiation therapy kills cancer cells by damaging their DNA (the molecules inside cells that carry genetic information and pass it from one generation to the next) . Radiation therapy can either damage DNA directly or create charged particles (free radicals) within the cells that can in turn damage the DNA. Radiation therapy can lead to dry mouth from exposure of salivary glands to radiation. The salivary glands lubricate the mouth with moisture or spit. Post-therapy, the salivary glands will resume functioning but rarely in the same fashion. Dry mouth caused by radiation can be a lifelong problem. The specifics of your brain cancer radiation therapy plan will be based on several factors, including the type and size of the brain tumour and the extent of disease. External beam radiation is commonly used for brain cancer. The area radiated typically includes the tumour and an area surrounding the tumour.