Radiation therapy for oral cancer

Radiation therapy uses high-energy rays or particles to destroy cancer cells.

Some people with oral cancer have radiation therapy. Your healthcare team will use what they know about the cancer and about your health to plan the type and amount of radiation, and when and how it is given.

You may have radiation therapy to:

• destroy the cancer cells in the body
• destroy cancer cells that may be left behind after surgery or chemotherapy to reduce the risk that the cancer will come back (called adjuvant therapy)
• relieve pain or control the symptoms of advanced oral cancer (called palliative therapy)

Radiation therapy and chemotherapy may be given during the same time period to treat oral cancer. This is called chemoradiation. Some chemotherapy drugs can help make radiation work better by making cancer cells more sensitive to radiation. Combining chemotherapy and radiation therapy can be more effective than either treatment on its own.

Before having radiation therapy to treat oral cancer, it's important to have a complete dental exam and have any necessary dental work done.

During external radiation therapy, a machine directs radiation through the skin to the tumour and some of the tissue around it. External radiation therapy is also called external beam radiation therapy. It is often used after surgery for oral cancer that has a high risk of coming back (recurring). If surgery isn't an option, radiation therapy may be used on its own.

Doctors may use the following external radiation techniques to accurately target the area to be treated and spare as much surrounding normal tissue as possible.

3D conformal radiation therapy (3D-CRT) has many beams of radiation directed at the tumour. The radiation oncologist uses a CT scan or an MRI to map the exact location and shape of the tumour. The radiation beams are then shaped and aimed at the tumour from different directions to treat the tumour from all angles. Each individual beam is fairly weak and less likely to damage normal tissue. A higher dose of radiation is delivered where the beams meet at the tumour.

Intensity-modulated radiation therapy (IMRT) is similar to 3D-CRT in that it delivers radiation from many different angles to treat the entire tumour. In addition to shaping and aiming the radiation beams, IMRT allows the radiation oncologist to adjust the strength (intensity) of the individual beams. This reduces the dose of radiation reaching nearby normal tissue while allowing a higher dose to be delivered to the tumour. It is useful for treating tumours in hard-to-reach areas.

Volumetric modulated arc therapy (VMAT) is an advanced form of IMRT that delivers a dose to the entire tumour in a 360-degree rotation. Most modern linear accelerators can deliver this type of treatment. This may shorten the daily treatment time.

During radiation therapy, your healthcare team protects healthy cells in the treatment area as much as possible. 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 and the treatment schedule. Tell your healthcare team if you have side effects that you think are from radiation therapy. The sooner you tell them of any problems, the sooner they can suggest ways to help you deal with them.

These are common side effects of radiation therapy for oral cancer:

• fatigue
• skin problems
• sore mouth, dry mouth and swallowing problems
• infection
• taste changes
• loss of appetite
• nausea and vomiting
• hair loss
• dental problems
• difficulty opening the jaw (called trismus)
• thyroid problems
• nerve damage
• damage to the jawbone (called osteoradionecrosis)

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