Radiation Therapy for Nasopharyngeal Cancer
Radiation therapy uses high-energy x-rays or particles to destroy cancer cells or slow their rate of growth. It is usually at least part of the main treatment for nasopharyngeal cancer (NPC) because most of these cancers are very sensitive to radiation.
For many cases of NPC, chemotherapy is given with radiation to try to increase its effects. This treatment, known as chemoradiation, can be better than radiation alone at fighting the cancer, but it also tends to have more side effects. (This is discussed more in the section, Chemotherapy for Nasopharyngeal Cancer.)
Radiation therapy is usually given both to the main nasopharyngeal tumor 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 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.
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. Radiation therapy is much like getting an x-ray, but the radiation is stronger. The procedure itself is painless. Each treatment lasts only a few minutes, although the setup time – getting you in place for treatment – takes longer. Most often, radiation treatments are given 5 days a week for about 7 weeks.
EBRT is often given using a technique such as intensity-modulated radiation therapy (IMRT) that focuses the radiation better and lowers the radiation exposure to nearby healthy tissues.
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 machines used to deliver this type of radiation are known as a Gamma Knife, X-Knife, CyberKnife, and Clinac.
Brachytherapy (internal radiation)
Another way to deliver radiation is to insert (implant) very thin metal rods or wires into or very near the cancer. Small pellets of radioactive materials are placed into the rods or wires. The radiation travels a very short distance, so it affects the cancer without causing much harm to nearby healthy body tissues.
The 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 implant is 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
Common side effects of external beam radiation to the head and neck include:
- Skin changes in the area where the radiation passes through, with redness or blistering
- Nausea and vomiting
- Fatigue (tiredness)
- Sores in the mouth and throat which can lead to trouble swallowing and weight loss from not eating
- Loss of taste
These side effects get better once radiation has stopped. Other side effects may not get better over time, such as:
- Problems with hearing or vision because of damage to certain nerves
- Damage to bones in the skull
- Tooth problems
- Damage to the salivary glands
Radiation to these areas can make any tooth problems that you already have worse and hard to fix. 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 advise removing some teeth before treatment to lessen the chance you will have problems later.
A major concern with radiation therapy for NPC is that it can damage the salivary glands. This damage can result in dry mouth that does not go away, making it hard to swallow food. Dry mouth can also lead to severe tooth decay. To help prevent dental problems, people treated with radiation to the head or neck area need to practice careful oral hygiene.
Dry mouth is less of a problem if radiotherapy techniques such as IMRT are used. Some of the damage to the salivary glands may also be lessened if a drug called amifostine (Ethyol®) is given before each radiation treatment. This drug can have bothersome side effects, though.
The thyroid gland is often damaged if the neck area is treated with external beam radiation. The damage doesn’t cause problems seen right way, so your doctor will watch your thyroid function with blood tests in the years after treatment. If your thyroid function goes down, pills to replace thyroid hormone may be needed.
The pituitary gland, which is responsible for controlling many hormones in the body, can also be damaged by treatment of a tumor in the nasopharynx. This can also be found with blood tests. If the damage is serious enough, this might require taking certain hormones to replace the ones that are missing.
The carotid arteries, which are major blood vessels in the neck that deliver blood to the brain, can sometimes become narrowed after radiation, which could raise a person’s risk of stroke or other problems. This usually takes several years to occur.
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.
Last Medical Review: January 15, 2015 Last Revised: August 8, 2016