Radiation therapy uses high-energy x-rays or particles to destroy cancer cells or slow their rate of growth. Radiation therapy can be used in several situations for oral and oropharyngeal cancers:
- It can be used as the main treatment for small cancers.
- Patients with larger cancers may need both surgery and radiation therapy or a combination of radiation therapy and chemotherapy or a targeted drug (see “Targeted therapy for oral cavity and oral pharyngeal cancer”).
- After surgery, radiation therapy can be used, either alone or with chemotherapy, as an additional (adjuvant) treatment to try to kill any small deposits of cancer that may not have been removed during surgery. This is known as adjuvant radiation therapy.
- Radiation may be used (along with chemotherapy) to try to shrink some larger cancers before surgery. This is called neoadjuvant therapy. In some cases this makes it possible to use less radical surgery and remove less tissue.
- Radiation therapy can also be used to relieve symptoms of more advanced cancer, such as pain, bleeding, trouble swallowing, and problems caused by bone metastases.
External beam radiation therapy
The most common way to give radiation for these cancers is to carefully focus a beam of radiation from a machine outside the body. This is known as external beam radiation therapy. To reduce the risk of side effects, doctors carefully figure out the exact dose needed and aim the beam as accurately as they can to hit the carefully outlined target.
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 into place for treatment — takes longer. Treatments are usually given 5 days a week for 6 to 7 weeks. Other schedules for radiation doses have been studied in clinical trials.
Hyperfractionation refers to giving the total radiation dose in a larger number of doses, for example giving 2 smaller doses per day instead of 1 larger dose.
Accelerated fractionation means giving 2 or more doses each day so that the radiation treatment is completed faster (3 weeks instead of 6 weeks, for instance).
Hyperfractionation and accelerated fractionation schedules may reduce the risk of cancer coming back in or near the place it started (called local recurrence) and may help some patients live longer. The drawback is that treatments given on these schedules also tend to have more severe side effects.
Radiation is often given using techniques that help doctors focus the radiation more precisely, such as such as three-dimensional conformal radiation therapy (3D-CRT) and intensity modulated radiation therapy (IMRT). These use the results of imaging tests such as MRI and special computer programs to precisely map the cancer’s location. Radiation beams are then shaped and aimed at the tumor from several directions, which makes the treatments less likely to damage normal tissues than older ways of giving external beam radiation.
Another way to deliver radiation is by placing radioactive materials directly into or near the cancer. This method is called internal radiation, interstitial radiation, or brachytherapy. The radiation travels only a very short distance, which limits its effects on nearby normal tissues.
Brachytherapy is not used often to treat oral cavity or oropharyngeal cancers because newer external radiation approaches, such as IMRT, are now very precise. When brachytherapy is used, it is most often combined with external radiation to treat early lip or mouth cancers.
Different types of brachytherapy may be used. In one form, hollow catheters (thin tubes) are placed into or around the tumor during surgery and are left in place for several days while the patient stays in the hospital. Radioactive materials are then inserted into the tubes for a short time each day.
In another form, small radioactive pellets (about the size and shape of a grain of rice) are placed directly into the tumor. The pellets give off low levels of radioactivity for several weeks and eventually lose their strength. The pellets themselves are left in place permanently and rarely cause any problems.
Possible side effects of radiation therapy
Radiation of the mouth and throat area can cause several short-term side effects, including:
- Skin changes like a sunburn or suntan on the head and neck that slowly fades away
- Loss of sense of taste
- Redness and soreness or even pain in the mouth and throat
Sometimes open sores develop in the mouth and throat, making it hard to eat and drink during treatment. Liquid feeding through a tube placed into the stomach may be needed. This is known as a gastrostomy or G tube (see the “Surgery for oral cavity and oropharyngeal cancer” section).
Radiotherapy may also cause long-lasting or permanent side effects:
Damage to the salivary glands: Permanent damage to the salivary (spit) glands can cause a dry mouth. This can lead to problems eating and swallowing.
The lack of saliva can also lead to tooth decay (cavities). People treated with radiation to the mouth or neck need to practice careful oral hygiene to help prevent this problem. Fluoride treatments may also help.
Newer radiotherapy techniques such as IMRT may help reduce this side effect. A drug called amifostine (Ethyol®) can also help reduce this side effect by limiting radiation damage to normal tissues. It is injected under the skin or into a vein a few minutes before each radiation treatment. Amifostine has side effects, such as low blood pressure, nausea, and vomiting, that can make it hard to tolerate.
Damage to the jaw bone: This problem, known as osteoradionecrosis of the jaw, can be a serious side effect of radiation treatment. This is more common after tooth infection, extraction, or trauma, and it can be hard to treat. The main symptom is pain in the jaw. In some cases, the bone actually breaks. Sometimes the fractured bone heals by itself, but often the damaged bone will have to be treated surgically.
To help prevent this problem, people getting radiation to the mouth or throat area need to see a dentist to have any problems with their teeth treated before radiation is started. In some cases, teeth may need to be removed.
Damage to the pituitary or thyroid gland: If the pituitary or thyroid gland is exposed to radiation, their production of hormones may decrease over time. This can lead to problems with metabolism that may need to be corrected with medicine.
Side effects are more severe if chemotherapy is given at the same time as radiation (chemoradiation). Both the radiation and chemotherapy side effects are worse, which can make this treatment hard to tolerate. For this reason, it’s important that anyone getting chemoradiation be in relatively good health before starting treatment, that they understand the possibility of serious side effects, and that they are treated at a medical center with a lot of experience with this approach.
More information on radiation therapy can be found in the “Radiation Therapy” section of our website, or in our document Understanding Radiation Therapy: A Guide for Patients and Families.
Last Revised: 01/27/2016