Radiation therapy uses high-energy x-rays or particles to destroy cancer cells or slow their growth.
Radiation therapy may be used:
- As the main treatment (alone or with chemotherapy) for some salivary gland cancers that can’t be removed by surgery because of the size or location of the tumor, or if a person can’t have (or doesn’t want) surgery
- After surgery (alone or with chemotherapy) to try to kill any cancer cells that might have been left behind, if the cancer has a higher chance coming back
- In people with advanced salivary gland cancer to help with symptoms such as pain, bleeding, or trouble swallowing
External beam radiation therapy, which focuses radiation from outside the body on the cancer, is the type of radiation therapy used most often to treat salivary gland cancer.
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. This may take a couple of hours or more on the first visit.
Most often, radiation treatments are given 5 days a week for 6 or 7 weeks. The length of treatment might be shorter if it’s only being used to relieve symptoms from cancer spread.
Getting radiation treatment is much like getting an x-ray, but the radiation dose is stronger and aimed more precisely at the cancer. The procedure itself is painless. Each treatment lasts only a few minutes, but the setup time – getting you into place for treatment – takes longer.
In recent years, doctors have found that newer forms of radiation therapy may work better than the standard treatment.
Accelerated hyperfractionated radiation therapy: In this approach, radiation is given twice a day over a shorter total length of time.
Three-dimensional conformal radiation therapy (3D-CRT): 3D-CRT uses the results of imaging tests such as MRI and special computers to precisely map the location of the tumor. Several radiation beams are then shaped and aimed at the tumor from different directions. Each beam alone is fairly weak, which makes it less likely to damage normal tissues, but the beams converge at the tumor to give a higher dose of radiation there.
Intensity modulated radiation therapy (IMRT): IMRT is an advanced form of 3D therapy. It uses a computer-driven machine that actually moves around the patient as it delivers radiation. In addition to shaping the beams and aiming them at the tumor from several angles, the intensity (strength) of the beams can be adjusted to limit the dose reaching the most sensitive nearby normal tissues. This may let the doctor give a higher dose to the tumor. Many major hospitals and cancer centers now use IMRT as the standard way to deliver external beam radiation.
Fast neutron beam radiation: Instead of using x-rays, neutron radiation therapy uses a beam of high-energy neutrons. Neutrons are neutral particles in atoms. Some studies have suggested that this type of radiation may be more effective, but it may also lead to more side effects. Neutron therapy machines are available in only a handful of cancer centers in the United States at this time.
Possible side effects
Radiation therapy may cause sunburn-like skin changes, nausea, vomiting, and fatigue. Often these go away after treatment.
Radiation therapy of the salivary glands can cause specific problems, because important structures in the head and neck might also get some radiation during treatment. The most common side effect is reduced saliva, which can lead to a dry mouth. Radiation can also cause a sore throat, sores in the mouth and throat, hoarseness, trouble swallowing, temporary loss of taste, bone pain, and bone damage. Radiation can make tooth problems worse, too. Most doctors advise that you have your teeth checked by a dentist before starting 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.
For most major salivary gland cancers, radiation is only given to the side of the face and neck with the cancer, which reduces the risk of serious long-term side effects. But in rare instances, both sides of your face and neck might need to be treated with radiation. This may damage other salivary glands, resulting in permanently dry mouth. This often causes problems with eating and swallowing and can lead to tooth decay.
Some of the damage to the salivary glands may be lessened if a drug called amifostine (Ethyol®) is given before each radiation treatment. This drug can be hard to tolerate, so it’s not helpful for everyone.
Radiation therapy might also damage your thyroid gland, which might not show up until months or even years later. Blood tests to check thyroid function will be done during follow up (after treatment is complete). Some patients might need to take pills to replace thyroid hormone at some point.
It’s 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. If you do have side effects, there are ways to relieve many of them, so be sure to discuss any symptoms with your cancer care team.
For more information on radiation therapy, see the Radiation Therapy section of our website or our document Understanding Radiation Therapy: A Guide for Patients and Families.
Last Revised: 03/03/2015