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Normal cell division is regulated by a specific gene. In cancerous tissue the cells are missing the gene or the gene has been transformed, this results in a group of cells displaying uncontrolled growth. These cells can also invade or intrude on and destroy adjacent tissues. The same cells can also metastasise and spread to other locations in the body though the blood and lymph node. The transformation of a normal cell to a cancerous cell can be caused by external factors called carcinogens which can be found in cigarette smoke, radiation, cancer can be caused by certain infections, or can be caused by a genetically inherited trait. There are several different ways that cancer can be managed or treated. This includes surgery, radiation therapy, chemotherapy, monoclonal antibody therapy and immunotherapy. Radiation therapy is the one of the most common methods of treating localised cancer cells.
Radiation Therapy on the Cancerous Level
Radiation therapy is used to destroy cancer cells and has been used to treat almost every type of solid tumour cancers, like brain, breast, lung, pancreas, stomach and prostate to name a few. It is can be administered externally by external beam therapy or internally using brachytherapy. External Radiotherapy treatment involves focusing a high energy radiation beam to a localised cancerous site; this confines the radiation to predetermined site. In brachytherapy, the doctors place a source of radiation close to the tumour using hollow needles, this therapy may be used alone or in conjunction with external therapy. Unfortunately both radiation therapies also damage neighbour cells, however normal cells have the innate ability to repair themselves unlike cancer cells which don't are resultantly destroyed by the treatment.
Radiation Therapy on the Cellular Level
In external or brachytherapy radiation therapy the tumour is attacked by either a beam or a small constant dose of ionising radiation. The radiation used consists of highly energised X-rays and gamma waves that have the ability to detach or ionise an electron from an atom or molecule. At low levels of radiation there is no detectable ionisation effect, unlike at the higher doses that are used for radiation therapy, there are a variety of outcomes. The radiation ionises the bonds in the cell's water molecules releasing hydroxyl free radicals. The hydroxyl free radicals attack the DNA molecules causing damage, mutations, and sometimes even break the DNA strands. The DNA is the basis of the genetic materials; the command centre in the cells, without functioning DNA the cancer cells can no longer function properly or repair themselves leading it to apoptosis. Apoptosis or "cell suicide" is the cells innate ability to destroy itself when it is irreparably damaged. Since cancer cells have lost the ability to detect that they are damaged and to destroy themselves; radiation restores the ability. The amount and length of the radiation treatment depends on the radiosensitivity of the cancer and also on the sensitivity of target zone. If damage to the local tissues is detrimental, then the amount of radiation may be limited.
Side effects of radiation therapy are related to the area treated; with most common effects being skin reactions, loss of appetite and fatigue. In rare occasions your white blood cell counts will be lowered making you more susceptible to infection. These effects may increase with the treatments but will subside as the treatments end.