Information about the Radiation Therapy

Treating with Radiation

The primary purpose of radiation therapy is to eliminate or shrink localized cancers (as opposed to cancers that have spread to distant parts of the body). The aim is to kill as many cancer cells as possible, while doing as little damage as possible to healthy tissues. In some cases, the purpose is to kill all cancer cells and achieve a cure. In other cases, when cure is not possible, the purpose is to alleviate symptoms by reducing the size of tumors that cause the symptoms.

For certain types of cancer, radiation therapy alone is the preferred treatment. However, radiation is often used in conjunction with surgery, chemotherapy, or both, and survival rates for combination therapy in these cases are greater than for any single type of therapy. Radiation therapy is also useful for organ and function preservation, such as laryngeal, breast, bladder and limb cancers. Size and location of the tumor frequently render the surgical option less desirable due to increased side effects. Radiation therapy can then be used to treat the cancer and control the disease with low morbidity.

Biological basis of Radiation therapy

High energy radiation kills cells by damaging their DNA and thus blocking their ability to divide and proliferate. Radiation kills normal cells about as well as cancer cells, but cells that are growing and dividing quickly (such as cancer cells, skin cells, blood cells, immune system cells, and digestive system cells) are most susceptible to radiation. Fortunately, most normal cells are better able to repair radiation damage than are cancer cells. Accordingly, radiation treatments are parceled into component treatments that are spaced throughout a given time interval (usually up to seven weeks). Thus, cells are given a chance to repair during the time between treatments. Since the repair rate of normal cells is greater than the repair rate of cancerous cells, a smaller fraction of the radiation-damaged cancerous cells will have been repaired by the time of the next treatment. This procedure is called "fractionation" because the total radiation dose is divided into fractions. Fractionation allows greater killing of cancer cells with ultimately less damage to the surrounding normal cells. Ideally all cancer cells will be dead after the last treatment session.

Risks and Benefits of Radiation

Radiation Therapy can be used to treat almost any type of cancer, anywhere in the body. When radiation is combined with surgery, the radiation treatments may be given pre-operatively. In this case, radiation will be used to decrease the size of a tumor to facilitate removal. More commonly, though, the radiation treatments are given post-operatively. Sometimes, radiation treatments may be given in combination with chemotherapy treatments. For many patients, radiation therapy will be the only treatment necessary for their cancer. Whatever the case, radiation therapy plays a very important part in cancer treatment. For any treatment of disease, there are always risks involved. This is also true of radiation therapy. In damaging cancer cells, some normal cells may also be damaged, resulting in side effects. The potential side effects will be explained to you by the Radiation Oncologist and the Radiation Oncology Nurse. All possible measures are taken to reduce the extent of any side effects. Many people complete their treatment with little or no difficulty at all.