Radiation Therapy for Oral Cavity and Oropharyngeal Cancer

Studies have shown that people who are treated at centers that treat a lot of head and neck cancers with radiation, tend to live longer. And because of the complicated types of surgeries, along with the need for coordination between cancer specialists to make a complete treatment plan, it’s very important to have treatment at cancer centers by radiation oncologists who have experience in treating these cancers.

Radiation therapy uses high-energy x-rays or particles to destroy cancer cells or slow their growth. Depending on the stage of the oral cavity or oropharyngeal cancer and other factors, radiation therapy might be used:

• Alone as the main treatment for small cancers or for people who can’t have surgery.
• After surgery (adjuvant therapy), either alone or with chemotherapy (chemoradiation), to try to kill any cancer cells that might have been left behind because they were too small to be seen with the naked eye during surgery. Radiation after surgery can also help lower the chance the cancer will come back in the same spot.
• Before surgery (neoadjuvant therapy) with chemotherapy (chemoradiation) or after chemotherapy to try to shrink some larger cancers. In some cases, this might make it possible to use less extensive surgery and remove less tissue.
• With a targeted drug for larger cancers, if chemotherapy is not an option.
• To help ease symptoms of advanced cancer, such as pain, bleeding, trouble swallowing, and problems caused by cancer spread to lungs or bones.
• To treat cancer that has come back after treatment (recurrence).

Chemoradiation (radiation given at the same time as chemotherapy) often works better than radiation alone, but it also has more side effects.

Radiation to this part of your body can cause problems for your teeth and gums, so it's important to see a dentist before starting treatment. A dentist can make sure your mouth is healthy before treatment. They might recommend that certain bad teeth be removed before you start radiation because this can increase your chance of infection. During and after treatment your dentist can help check for and treat any problems that may come up, such as infection or tooth and bone damage.

Quit smoking before oral and oropharyngeal cancer treatment

If you smoke, it is important to quit. Smoking during radiation treatment can cause more side effects and a poor response to radiation, which can raise your risk of the cancer coming back (recurrence).  Smoking after treatment also increases the chance of getting a new cancer. Quitting smoking for good (before treatment starts, if possible) is the best way to improve your chances for successful treatment. It is never too late to quit. For help, see How To Quit Using Tobacco.

External beam radiation used for oral and oropharyngeal cancers

External beam radiation therapy (EBRT) is the type of radiation therapy most often used to treat oral cavity or oropharyngeal cancer or its spread to other organs. It focuses radiation from a source outside the body onto the cancer.

Before EBRT, a somewhat flexible but sturdy mesh head and neck mask might be made to hold your head, neck, and shoulders in the exact same position for each treatment. Some people might feel a bit confined while this mask is on and might need to ask for medicine to help them relax during the treatment. Sometimes, the mask can be adjusted so that it is not too constricting. Discuss your options with your radiation oncologist. You might also be fitted for a bite block that you hold in your mouth during treatment

Treatment is much like getting an x-ray, but the radiation dose is stronger. The procedure itself is without pain and each treatment lasts only a few minutes. The setup time (getting you into place for treatment) often takes longer.

Different types of EBRT

There are also more advanced EBRT techniques that help doctors focus the radiation more precisely.

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

Intensity modulated radiation therapy (IMRT) is a form of 3D-CRT. It uses a computer-driven machine that actually 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 limit the dose reaching nearby normal tissues. This may let the doctor deliver a higher dose to the tumor.

Proton beam radiation therapy focuses beams of protons instead of x-rays on the cancer. Unlike x-rays, which go through the patient and release radiation both before and after they hit the tumor, protons only travel a certain distance, so the tissues behind the tumor are exposed to very little radiation. Even the tissues in front of the tumor see less radiation than the tumor itself. This means that proton beam radiation can deliver radiation to the cancer while doing less damage to nearby normal tissues. Because there are so many critical structures close by, proton beam radiation can be used to treat certain tumors of the oral cavity or oropharynx. Proton therapy can be a safe option in certain cases when using x-rays is not.

Proton therapy is not widely available in the United States. The machines needed to make protons are very expensive. Proton therapy might also not be covered by all insurance companies at this time.

Different treatment schedules for EBRT

Standard EBRT for oral cavity or oropharyngeal cancers is usually given in daily fractions (doses) 5 days a week for about 7 weeks. But sometimes other schedules might be used:

• Hyperfractionation radiation is a slightly lower radiation dose given more than once a day (for example, twice a day for 7 weeks). 
• Accelerated fractionation radiation is the standard dose of radiation given each day but over a shorter time (5 to 6 weeks) instead of the usual 7 weeks (for example, radiation is given 6 days a week over 5 weeks instead of the standard 5 days a week for 7 weeks). 
• Hypofractionation radiation is a slightly higher radiation dose given each day to lessen the number of treatments (for example, a higher radiation dose is given each day for 6 weeks, not the standard 7 weeks).

Hyperfractionation and accelerated fractionation schedules may reduce the risk of cancer coming back in or near the place it started (called local recurrence) and might help some people live longer compared to standard EBRT. The drawback is that treatments given on these schedules also tend to have more severe side effects. Adding chemotherapy to these treatment schedules (chemoradiation) doesn't appear to improve outcomes more.

Brachytherapy for oral and oropharyngeal cancers

Brachytherapy is rarely used to treat oral cavity or oropharyngeal cancers as a first treatment, but it might be used if the cancer recurs (comes back).

Possible side effects of radiation therapy for oral cavity or oropharyngeal cancer

If you are going to get radiation therapy, it’s important to ask your doctor about the possible side effects so you know what to expect.

Radiation to the mouth and throat area can cause several short-term side effects depending on where the radiation is aimed and can include:

• Skin changes like a sunburn or suntan in the treated area
• Hoarseness
• Loss of taste
• Redness, soreness, or even pain in the mouth and throat
• Dry mouth
• Trouble swallowing
• Feeling tired
• Open sores in the mouth and throat

Long-lasting or permanent side effects of radiation therapy

Poor nutrition and trouble swallowing: Many people treated with radiation to the oral cavity and throat area have painful sores in the mouth and throat that can make it very hard to eat and drink. This can lead to weight loss and poor nutrition. The sores heal with time after the radiation ends, but some people continue to have problems swallowing long after treatment ends because of the tightening of the muscles caused by radiation. Ask your speech pathologist about swallowing exercises you can do to help keep those muscles working and increase your chance of eating normally after treatment. Liquid feeding through a tube placed into the stomach might be needed. (See Surgery for Oral Cavity and Oropharyngeal Cancer for more on tube feedings.)

Dry mouth: Damage to the salivary (spit) glands from radiation can cause a dry mouth that doesn't get better with time. This can lead to discomfort and problems eating and swallowing, as well as damage to the jaw bone.

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 and see their dentist regularly. Fluoride treatments may also help.

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 repaired with surgery.

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.

Thyroid problems: Radiation might damage your thyroid gland. Your doctor will do blood tests regularly to see how well your thyroid is working. You may need treatment if it's been damaged and is not working well. 

Lymphedema: Some people treated with radiation therapy might be at risk of developing lymphedema in the head and neck areas that were treated. These areas can become swollen and firm. This can be worse if the person also had surgery. Sometimes, medicines, physical therapy, or massage therapy might be helpful.

Damage to the carotid artery: Radiation to the neck area might increase a person’s risk of stroke many years after treatment. This might be because of health problems that were already present before radiation such as narrowing of the artery or an increase in plaques which can both decrease blood flow. People who smoke are also damaging their arteries. Because of this some doctors might order regular ultrasounds for you after treatment, to keep an eye on the arteries.