What is radiation therapy?|
Cancer is one of the most major causes of death today. For over 50 years, radiation therapy has played a vital role in the treatment and control of this disease. Over these years, the field has evolved to treat both malignant disease and occasionally benign conditions. Radiation therapy, or radiotherapy, is the use of high energy, penetrating radiation to kill cancer cells.
The purpose of radiation therapy is to eliminate or shrink localised cancers. The aim is to kill as many cancer cells as possible, while doing as little damage as possible to healthy tissues. The procedure may be used in conjunction with surgery (and possibly chemotherapy); however, it is especially useful when surgical procedures cannot remove an entire tumor without damaging the function of surrounding organs. The treatment of choice for each case must be considered on its merits.
Basics of radiation therapy
High-energy radiation kills cells by damaging their DNA and thus blocking their ability to divide and proliferate. Unfortunately, radiation kills normal cells nearly as well as cancer cells, cells that are growing and dividing rapidly, such as cancer cells, skin cells, blood cells and immune and digestive system cells, are most vulnerable to radiation. Fortunately, most normal cells are better able to repair radiation damage than are cancer cells. For this reason, the total radiation dose in a treatment is divided into fractions over time. This "fractionation" allows greater killing of cancer cells with less overall damage to the surrounding normal cells.
Preparation for radiation therapy
The first step in therapy is to assess the nature and extent of the disease. The site, stage (geographical extent of the disease), grade (type of tumor) and length of history of the condition are all determined. It is also important to know whether the patient is fit enough to undergo radical treatment. Before starting radiation, the size and location of the patient's tumor, and the nature of the surrounding tissue that may be in the path of the radiation beam, must be determined as accurately as possible. Magnetic resonance imaging (MRI) and computed tomography scans (CT scans) are used to provide detailed images of the tumor.
Radiation and surgery
A combination of radiation and surgery often produces the best results for the patient. Sometimes surgery is recommended for the primary tumour with radiotherapy to the lymph node drainage areas. Lymph nodes drain the fluid that lies around cells, outside of the blood stream. They are a major route for the spread of cancer, and are often the first secondary sites of metastases.
Sometimes the reverse is recommended. More often the question is simply one of pre-operative or post-operative radiation. Generally speaking, if combined therapy is being considered, it is preferable to give the radiation prior to surgery. Exceptions to this rule are for instance, when the diagnosis and extent of the disease are only obtained following surgery.
Immediately following radiation an inflammatory reaction sets in which begins to subside after one month. This slows the healing process, and thus, a delay of six weeks is recommended as the ideal gap between radiation and surgery.
Palliative Radiation Therapy
Palliative therapy is targeted at relieving symptoms, or reducing their severity, without curing the underlying disease. Such treatment should be closely coordinated with the chemotherapeutic management of the case. When localised symptoms develop, radiotherapy often provides the most rapid means of relief. Severe pain is often relieved with a short course of radiation therapy. Bleeding can also often be controlled with small dose of radiation. Acute haemorrhage is one emergency situation where radiotherapy may be of value. Prompt use of a Radium pack can often control the bleeding within a few<