A common treatment for cancer is radiation therapy. Radiation therapy can be used as primary treatment to shrink the tumor, or after primary treatment (such as surgery or chemotherapy) to prevent remaining cells from dividing. The two main goals of radiation therapy are to either treat the cancer, or to help relieve symptoms such as pressure and pain (palliative care).

Radiation therapy — also called radiotherapy or irradiation — is the use of high-energy x-rays, gamma rays, radioactive isotopes, or electron beams to kill cancer cells. Radiation destroys cancer cells by a process called ionization. The cancer cells either die immediately from direct contact with the radiation beam, or the damage to the chromosomes and DNA causes the cancerous cells to stop dividing. Because radiation can also harm healthy cells, doctors carefully limit the amount of radiation a part of the body receives and spread the treatment over a period of time. They also shield as much surrounding healthy tissue as possible while they administer the radiation. Radiation is generally given daily five days a week. The duration of treatment can range from two to eight weeks depending on the tumor, dosage, and type of treatment used. Board-certified specialists trained to evaluate and treat cancer patients are used to administer radiation therapy.

Types of Radiation Therapy

There are many different methods of delivering radiation therapy. Your radiation oncologist along with your primary physician, medical oncologist, and surgeon will determine the dose, administration, and duration of treatment.

External beam radiation is delivered from a machine outside the body that does not touch your skin or the tumor. The machine aims radiation through the skin directly at the tumor and surrounding tissue to destroy the primary tumor and any nearby cancer cells. Before radiation treatments begin, your radiation oncologist will plan the dosage and how to direct the beam with the help of x-rays, CT scans, or other imaging studies in a process called simulation. During simulation you will lie on a table, and your doctors will use a simulator machine to identify the area of your body where you will receive radiation (the treatment field). Although simulation can take up to two hours, the actual radiation treatments will only take a few minutes. Depending on the type of treatment you will be receiving, devices to keep you from moving called body molds may also be made during simulation. At the end of the simulation visit, very small ink marks or tattoos may be put on your body to identify the area to be treated. These marks help the radiation technologists accurately set up your treatment fields each day.

External radiation does not cause your body to become radioactive. Being around others poses no risk of radiation exposure.

With internal radiation, also called brachytherapy or interstitial radiation, doctors implant a radiation source as close as possible to the primary tumor and surrounding cells. The type of implant and the implantation method depends on the size and location of the tumor. The implant may be permanent or temporary. This type of treatment allows doctors to deliver higher doses of radiation to the tumor with minimal exposure to surrounding tissue. Internal radiation is done by implanting the radioactive material into the tumor either through a thin wire, catheter, or seed.

While the actual radiation treatment is painless, some patients do have residual side effects. Side effects of radiation therapy are related to the area being treated and vary from patient to patient. The most common side effects of radiation therapy include fatigue, sensitive or irritated skin to the area receiving radiation, and in some cases, loss of hair in the area being treated. Your radiation oncologist and nurse will discuss the side effects you might experience, how long they might last, and how to deal with them.

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