One of the treatments often recommended for the treatment of cancer is radiation therapy. Radiation therapy uses ionized radiation in order to target and control cell growth. The ionized radiation damages the DNA in cancer cells, causing cell death. In order to prevent damage to healthy tissue, radiation is beamed from several different angles in order to put the greatest amount of radiation into the tumor. As early as 1895, doctors were using x-rays in order to treat cancer.
As different cancers respond to different therapies, radiation therapy is used on types of cancers known for their radiosensitivity. Such examples include leukemia and lymphoma. Other types of cancer would require such high does of radiation therapy that it is often not recommended. The amount of radiation used in therapy is measured in gray (Gy). Lymphomas, for example, are treated with doses between 20 to 40 Gy.
While radiation therapy is itself entirely painless, and low-dose treatments may not have any side effects, other doses of radiation therapy can cause extreme side effects. The most common side effect is nausea and vomiting, but is often more of a psychological reaction than an effect of the radiation. Some side effects may appear months or even year after radiation therapy. Fibrosis is a type of long-term side effect from radiation therapy, as irradiated tissues will become less elastic over the course of time.