Radiation therapy for oropharyngeal cancer

Radiation therapy uses high-energy rays or particles to destroy cancer cells. Many people with oropharyngeal cancer have radiation therapy. Your healthcare team will consider your personal needs to plan the type and amount of radiation, and when and how it is given. You may also receive other treatments.

Radiation therapy is often combined with chemotherapy to treat oropharyngeal cancer. This is called chemoradiation. The 2 treatments are given during the same time period. The chemotherapy makes the radiation more effective.

Radiation therapy is given for different reasons. You may have radiation therapy or chemoradiation:

• as the main treatment for small tumours
• to destroy any cancer cells left behind after surgery to reduce the risk that the cancer will come back (recur) (called adjuvant therapy)
• to shrink a tumour before surgery (called neoadjuvant therapy)
• to relieve pain or control the symptoms of advanced oropharyngeal cancer (called palliative therapy)
• to treat cancer that comes back after other treatments

Talk to your healthcare team to find out what you need to do before radiation therapy begins. They may discuss any or all of the following, depending on your personal needs.

Smoking during treatment may make radiation therapy for oropharyngeal cancer less effective. Smoking may also make side effects from radiation therapy worse.

If you smoke, your healthcare team will talk to you about how they can help you quit before you start radiation therapy.

It is important to have a complete dental exam before radiation therapy begins to prevent dental problems. Your dentist will determine if you need to have any dental work done before treatment, such as having unhealthy teeth removed. They will also develop a dental care plan for you to follow after radiation therapy.

Many people have a custom immobilization mask made before external radiation therapy is given to the head and neck. The mask makes sure that you don’t move during treatment and that radiation is directed at exactly the same place each time. You will need to wear it during treatment planning and all radiation treatments.

You may have a gastrostomy tube (G-tube) placed before having radiation therapy for oropharyngeal cancer. A G-tube is a feeding tube that is passed through the skin into the stomach. A G-tube will let foods and liquids pass directly into your stomach (called enteral feeding) when you find it too difficult to eat or drink. G-tubes can be placed using a flexible scope that goes through your mouth or nose, guided by an x-ray, or by creating a small surgical opening from your skin into your stomach.

Radiation therapy to the head and neck can make swallowing difficult and painful, so a gastrostomy tube can help make sure you will get the nutrition you need.

Find out more about tube feeding.

Radiation therapy for oropharyngeal cancer can cause nerve damage or fluid buildup in the middle ear. This can affect your hearing, so it is important to protect your ears as much as possible.

The healthcare team may place tubes in one or both ears before radiation starts. These tubes drain fluid and air from the middle ear. They usually fall out on their own, but the doctor might have to remove them after treatment in some cases.

Both the thyroid and pituitary glands may be in the area treated with radiation therapy for oropharyngeal cancer. Radiation can affect these structures, so the healthcare team takes special care to protect them during treatment. They will also do blood tests before, during and after radiation therapy to check how well the thyroid and pituitary glands are working.

During external radiation therapy, a machine directs radiation through the skin to the tumour and some of the tissue around it.

Oropharyngeal cancer that develops at the base of tongue or on the soft palate often spreads to lymph nodes on both sides of the neck. Radiation is often given to lymph nodes on both sides of the neck to destroy cancer cells.

Oropharyngeal cancer that starts in a tonsil doesn’t usually spread to both sides of the neck until it is very advanced. Radiation may only be given to the same side of the neck as the tumour.

External radiation therapy is usually given once a day for 5 days a week over a period of 5 to 7 weeks. The healthcare team will take special care to protect the surrounding tissues from the radiation as much as possible. These tissues include the salivary glands, the thyroid gland and the larynx (voice box).

There are different types of external radiation therapy that may be used to treat oropharyngeal cancer.

3D conformal radiation therapy (3D CRT) delivers radiation to the tumour from different directions. The radiation beams are all the same strength.

Intensity-modulated radiation therapy (IMRT) uses computer-generated images to deliver radiation directly to the tumour or lymph nodes from many different angles. A higher dose can be given to the tumour while the normal tissues near the tumour get less radiation. It may be used for oropharyngeal cancer when there is little risk that cancer cells have spread into the surrounding tissue.

Side effects can happen with any type of treatment for oropharyngeal cancer, but everyone’s experience is different. Some people have many side effects. Other people have few or none at all.

During radiation therapy, the healthcare team protects healthy cells in the treatment area as much as possible. But damage to healthy cells happens and causes side effects. Side effects can happen any time during, immediately after or a few days or weeks after radiation therapy. Most severe side effects do not occur until 3 to 4 weeks into therapy. Sometimes late side effects develop months or years after radiation therapy. Many side effects go away on their own or can be treated, but some side effects are permanent.

Side effects of radiation therapy will depend mainly on the size of the area being treated, the specific area or organs being treated, the total dose of radiation, whether chemotherapy is given at the same time (chemoradiation) and the treatment schedule. Chemotherapy makes the radiation more effective in killing cancer cells, but it also makes the side effects from radiation worse.

Some common side effects of radiation therapy used for oropharyngeal cancer are:

• skin problems
• fatigue
• sore mouth and throat
• dry mouth
• taste changes
• hoarseness
• thickened saliva
• difficulty hearing
• vision changes
• low thyroid hormone (hypothyroidism)
• tooth decay
• difficulty opening the jaw (called trismus)
• infection and breakdown of surrounding bones (osteoradionecrosis)

Tell your healthcare team if you have these side effects or others you think might be from radiation therapy. The sooner you tell them of any problems, the sooner they can suggest ways to help you deal with them.

Find out more about radiation therapy and side effects of radiation therapy. To make the decisions that are right for you, ask your healthcare team questions about radiation therapy.