Radiation Treatment

Radiation treatment, along with surgery and chemotherapy, is one of the most common treatments for cancer.

What is radiation therapy?
Radiation is a general term for rays of energy, either in the form of electromagnetic waves or subatomic particles. In radiation treatments for cancer, high-energy radiation rays are used to cause injury to diseased tissue, the cancer cells. Radiation is invisible. X-rays are a form of radiation and the most common type of radiation used in radiation therapies.

Radiation treatments are not used in all types of cancers but can be a useful part of treatment, oftentimes along with other treatments, for some. Some cancers and other tumors are very sensitive to the effects of radiation while others are relatively resistant to its effects.

How does radiation therapy work?
High-energy radiation is damaging to cells. It causes damage to various parts of cells in the body but have a profound impact on the genetic material, DNA, of the cell. This DNA damage can lead to death of the cell. Therefore, cells which are dividing rapidly, and duplicating their DNA in the process, are particularly susceptible to radiation. Because cancer cells are typically dividing and growing quickly, they tend to be more susceptible to the injurious effects of radiation than other cells.

Therefore, radiation delivered to cancer cells can cause the cells to become dysfunctional and die. However, surrounding normal cells can be damaged by radiation as well. This impact is most profound on tissues which have many dividing cells, such as skin, hair follicles, the lining of the digestive tract and the bone marrow (which makes blood cells). Radiation delivered to these and other normal tissues can cause injury to these areas as well and is one of the potential side effects of radiation treatment.

How is radiation delivered?
In the distant past, radiation was delivered to the body of cancer victims in large beams that often exposed large areas of the body to radiation, and therefore to the side effects of radiation. However, as medical technology has advanced, better techniques to focus radiation just on the tumor have evolved. Various forms of focused beam radiation has become the norm, limiting exposure of normal tissues to radiation while maximizing the dose of radiation delivered to the tumor.

The most focused form of radiation is in so-called radiosurgery techniques, originally developed for use in brain tumors but now employed for some other types of cancer as well. In these techniques, several small rays of radiation are focused on the tumor from many different angles. Therefore, the exposure from any one ray to the surrounding normal tissues is minimized while the additive effect on the tumor itself results in a large dose of radiation to the tumor.

Side Effects of Radiation Treatment
Like any treatment, there are potential side effects of cancer treatments with radiation. As mentioned previously, radiation is damaging to many normal tissues and can cause symptoms in those tissues which are exposed to the radiation. Some common symptoms of radiation injury (if the tissue is exposed to enough radiation) include dry, thin skin, hair loss, radiation necrosis, swelling, digestive problems, anemia and/or immunosuppression (with bone marrow radiation exposure). Additionally, some tissues, if exposed to radiation, can develop other tumors or cancer in the future because of the damage to its DNA