Radiotherapy for Head and Neck Cancer
Your Questions Answered
Most types of head and neck cancer start in the cells lining the open cavities of the head and neck, such as the sinuses, nasal cavity, mouth, or throat. Other kinds of head and neck cancer can occur in the salivary glands. These glands produce the fluid, called “saliva” or spit, that keeps your mouth and throat moist. Cancer of the brain and thyroid is not classified as head and neck cancer.
According to the National Cancer Institute, head and neck cancer accounts for nearly three to five percent of all cancer in the United States. These types of cancer are more common in men and in people older than age 50. Tobacco and alcohol use are common risk factors for this cancer.
What is radiation therapy?
To treat cancer, high-energy radiation is delivered to cancer cells or a tumor. Radiation therapy works in two ways:
- Radiation can stop or slow the growth of the cancer.
- Radiation can shrink tumors, reduce some symptoms, and relieve pain.
Radiation therapy starts with a plan. Your doctors will make a detailed radiation plan for your treatment. The plan includes where to aim the radiation beams and how much radiation you should get. The goal of the plan is to provide the right amount of radiation to stop your tumor from growing or shrink it. The doctors want to protect you from any harm caused by the radiation, especially to the healthy cells around the tumor.
Radiation therapy does not kill cancer cells right away. You may need several days or weeks of treatment with radiation before cancer cells start to die. Cancer cells will keep dying for weeks or months after radiation therapy is finished.
Doctors use different systems and tools to make the radiation therapy plan and deliver your radiation therapy. The approach your doctor may use to target the tumor, aim the radiation beams, and change the strength of the beams while they are being given may change over time. Using different beam strengths may help protect you from the side effects of radiation.
What are the side effects of radiation therapy?
Everyone is different. Radiation therapy can cause damage to normal, healthy cells near and around your cancer. The damage may cause side effects. These side effects can be very different for different people. Your side effects may depend on the dose and type of radiation used, site of your cancer, stage of your cancer, and your age. Side effects can appear around two weeks after the first radiation treatment or much later and can include:
- Mouth sores (feels like little cuts or ulcers in your mouth)
- Dry mouth (also called xerostomia)
- Pain or difficulty with swallowing
- Changes in taste or smell
- Changes in the sound of your voice
- Jaw stiffness and jaw bone decay
- Changes in your skin
- Feeling tired.
What impact can these side effects have?
Radiation therapy does not hurt when it is given. Some of the side effects can hurt or affect your quality of life, even when the radiation helps to stop or slow down your cancer. Some side effects last only a few days. Other side effects can last weeks, months, or longer.
Some side effects, like dry mouth, may not ever get better. Your saliva is used for many things. Saliva is needed as you eat to help you swallow your food. Saliva also helps to protect you from tooth decay, as well as tongue and gum disease, by keeping bacteria from settling on your teeth, tongue, and gums. Saliva even plays a role in speaking.
What are the differences between radiation systems?
There are four external-beam radiation systems that doctors can use to treat your cancer. The first three of these have been used successfully to treat head and neck cancer for a number of years. The oldest system is called Two-Dimensional Radiation Therapy, or 2DRT . This system targets the tumor using a two-dimensional image, much like a picture or photograph. The beams can only be aimed at a few angles, and they do not change strength while they are being given. 2DRT is not used as often as the newer systems.
A newer system is called Three-Dimensional Conformal Radiation Therapy, or 3DCRT. This system uses three-dimensional images that let doctors better target the tumor. The images are made with a computed tomography (CT) or magnetic resonance imaging (MRI) machine. The beams can be aimed at more angles than 2DRT to limit the amount of radiation to the normal areas around the tumor.
A more recent system is called Intensity-Modulated Radiation Therapy, or IMRT. This system is similar to 3DCRT, but the doctor can adjust the amount of radiation you get from each beam. This is done to try to reduce injury to the healthy areas around the tumor.
Another system uses a different kind of energy beam to treat your tumor. This system is called Proton-Beam Radiation Therapy, or PBRT. There is very little information about how well this form of radiation therapy works, and it is not widely used.
Which type of radiation therapy is most effective for my cancer?
Doctors do not know if one type of radiation therapy is more effective than others in stopping or slowing down the growth of your head and neck cancer. In addition, doctors do not know if any one type of radiation therapy will control your cancer better or help you live longer.
There is some evidence that IMRT causes less damage to the glands that make your saliva when compared to 2DRT or 3DCRT. Early results from a recent study suggest that when people were examined one year after treatment, those who were treated with IMRT experienced dry mouth less often than those who were treated with 2DRT or 3DCRT. While doctors think that IMRT may help avoid damage to other normal organs in the head and neck – such as your eyes, brain, and other glands – they do not know this for sure.
The skill and experience of your doctors in using each type of radiation therapy may be important. The current studies were conducted in centers associated with universities and medical schools. Doctors do not know if the results are different in other types of medical centers. In addition, doctors do not know how the side effects of PBRT compare to the other three types of radiation therapy.
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Source: U.S. Department of Health and Human Services Agency for Healthcare Research and Quality, www.ahrq.gov
This article was published in Coping® with Cancer magazine, May/June 2011.