Radiation therapy uses high-energy x-rays or particles to destroy cancer cells or slow their rate of growth. It is usually the main form of treatment for NPC because most cases are very sensitive to radiation.

Treatment is usually given both to the main nasopharyngeal mass and to nearby lymph nodes in the neck. Even if the lymph nodes are not abnormally firm or large, radiation is still used in case a few cancer cells have spread to there. If the lymph nodes are known to have cancer cells, higher radiation doses are used.

Different types of radiation therapy can be used to treat NPC:

External beam radiation therapy (EBRT)

This type of radiation therapy uses x-rays from a machine outside the patient's body to kill cancer cells. It is the most common form of radiation therapy for NPC.

The treatment is much like getting an x-ray, but the radiation is more intense. The procedure itself is painless. Before your treatments start, the radiation team will take careful measurements to determine the correct angles for aiming the radiation beams and the proper dose of radiation. Each treatment lasts only a few minutes, although the setup time -- getting you into place for treatment -- usually takes longer. Most often, radiation treatments are given 5 days a week for several weeks.

Standard (conventional) EBRT is used much less often than in the past. Using newer techniques, doctors can more accurately treat nasopharyngeal cancers while reducing the radiation exposure to nearby healthy tissues. This may offer a better chance of increasing the success rate and reducing side effects. Many doctors now recommend using these newer approaches when they are available.

Three-dimensional conformal radiation therapy (3D-CRT) uses special computers to precisely map the location of the tumor(s). Radiation beams are shaped and aimed at the tumor(s) from several directions, which makes it less likely to damage normal tissues.

Intensity-modulated radiation therapy (IMRT) is an advanced form of 3D therapy. It uses a computer-driven machine that moves around the patient as it delivers radiation. Along with shaping the beams and aiming them at the tumor from several angles, the intensity (strength) of the beams can be adjusted to minimize the dose reaching the most sensitive normal tissues. Many major hospitals and cancer centers are now able to provide IMRT.

Stereotactic radiosurgery is a type of radiation treatment that delivers a large, precise radiation dose to the tumor area in a single session. (There is no actual "surgery" involved in this treatment.) The radiation may be delivered in 2 ways.

In one approach, radiation beams are focused at the tumor from hundreds of different angles for a short period of time. The machine used to deliver this type of radiation is known as a Gamma Knife.

Another approach uses a movable linear accelerator (a machine that creates radiation) that is controlled by a computer. Instead of delivering many beams at once, this machine moves around to deliver radiation to the tumor from different angles. Several machines, with names such as X-Knife, CyberKnife, and Clinac, do stereotactic radiosurgery in this way.

Recently, doctors have been adding chemotherapy to the radiation to try to increase its effects. When chemotherapy is used with radiation treatment, studies have shown the tumor shrinks more and the chance of spread elsewhere is lower.

Brachytherapy (internal radiation)

Another way to deliver radiation is to insert (implant) very thin metal rods or wires containing radioactive materials into or very near the cancer. The radiation travels a very short distance, so it affects the cancer without causing much harm to nearby healthy body tissues.

An implant is usually left in place for several days while the patient stays in a private hospital room. The length of time that visitors, nurses, and other caregivers can spend with the patient may be limited because of potential radiation exposure, but this depends on the type of radiation. The implants are removed before the patient goes home.

Brachytherapy may be used if the cancer comes back after external beam radiation therapy (although stereotactic radiosurgery may be used instead, as it is less invasive). Sometimes, internal and external beam radiation therapy are used together.

Possible side effects of radiation therapy

External beam radiation may cause sunburn-like skin changes, nausea, vomiting, and fatigue. Often these go away after treatment.

Radiation therapy of NPC can cause specific problems, because several important structures in the head and neck may also get some radiation during treatment.

A major concern with radiation therapy is that it often damages the salivary glands, which can result in a permanently dry mouth and nose. This can cause problems with eating and swallowing and can promote tooth decay. Most doctors advise that you have your teeth checked by a dentist before you have radiation therapy to the head or neck area. In some cases, the dentist may even recommend removing some teeth before treatment to lessen the chance you will have problems later.

Some of the damage to the salivary glands may be lessened if a drug called amifostine (Ethyol®) is given before each radiation treatment. There may also be fewer problems if IMRT is used.

Radiation can also cause sore throat, sores in the mouth, hoarseness, trouble swallowing and eating, loss of taste, and damage to bones in the skull. If certain nerves get radiation, hearing or vision may be affected.

If the neck area is treated with external beam radiation, the thyroid gland may be damaged. Pills to replace thyroid hormone may be needed after treatment.

The pituitary gland, which is responsible for controlling hormones, can be damaged also. Finally, the carotid artery, which is the major blood vessel delivering blood to the brain, can sometimes become narrowed after radiation. This usually takes several years.

It is important to discuss the possible side effects of radiation therapy with your doctor before starting treatment, and to make sure everything is being done to try to limit these side effects as much as possible.

For more general information about radiation therapy, please see the separate American Cancer Society document, Understanding Radiation Therapy: A Guide for Patients and Families.

Last Medical Review: 01/21/2009
Last Revised: 01/21/2009