Radiation Treatments for Head & Neck Cancers
Head and neck cancers account for about 4% of all adult cancers in the United States. Approximately 39,000 new cases are diagnosed each year.* Although most early-stage head and neck cancers have high cure rates,
as many as two-thirds of the cases are diagnosed when the disease is in an advanced stage, treatment is difficult, and surgery is often not recommended. A common form of treatment for head and neck cancers is radiation therapy. Recent advances in radiotherapy technology have improved success rates while reducing daily treatment times.
Your treatment plan will depend on several factors, including the exact location of the tumor, the stage of the disease, and your age and general health. Although radiation therapy is often used by itself, it can also be used before surgery to shrink the tumor, after surgery to target any remaining cancer cells, and at the same time as chemotherapy.
The head and neck region is home to delicate organs and tissues, which are typically sensitive to damage, discomfort, and scarring. Radiotherapy technology acts to interrupt the growth of these types of cancers, and in some cases remove them.
Most head and neck cancers originate in the cells that line the area's mucosal surfaces. Mucosal surfaces are the moist tissues that line the hollow organs and cavities of the body and are open to the environment, such as the mouth, nose and throat. These types of head and neck cancers are often referred to as squamous cell carcinoma. Some head and neck cancers begin in other types of cells. For example, cancers that begin in glandular cells are called adenocarcinoma.
Head and neck cancers can originate in the following areas:
- Oral cavity. Includes the lips, gums, front two-thirds of the tongue, the inside of the cheeks, the bottom of the mouth under the tongue, the hard palate at the top of the mouth, and the small area behind the wisdom teeth.
- Salivary glands. The major salivary glands are in the bottom of the mouth and near the jawbone.
- Nasal cavity and paranasal sinuses. The nasal cavity is the space inside the nose. The paranasal sinuses are small spaces in the bones of the head surrounding the nose.
- Pharynx. The pharynx is a tube about five inches long that starts behind the nose and leads to the esophagus (the tube that goes to the stomach) and the trachea (the tube that goes to the lungs). The pharynx has three parts: The nasopharynx (upper part of the pharynx, behind the nose), the oropharynx (middle part of the pharynx, and includes the back of the mouth, base of the tongue, and tonsils), and hypopharynx (the lower part of the pharynx).
- Lymph nodes. These can be found in the upper part of the neck.
Cancers of the brain, eye, thyroid, and esophagus are not considered to be head and neck cancers, nor are cancers of the scalp, skin, muscles, and bones of the head and neck.
Treatment Techniques for Head and Neck Cancers
There are two broad categories of radiation therapy; both are designed to target the tumor precisely while minimizing exposure to the healthy surrounding tissue. In the first category, external beam radiation therapy, the radiation is usually delivered by a machine called a linear accelerator, or linac, which focuses a high-energy x-ray beam into your tumor site from outside your body. In the second treatment category, the radiation is delivered by radioactive material placed inside the body near the cancer cells—a procedure called brachytherapy (also called implant radiation therapy or internal radiation therapy).
External Beam Radiation Therapy
IGRT, or image-guided radiation therapy, uses sophisticated computer software to analyze a series of image scans of your tumor to create a detailed, three-dimensional picture of the site and your surrounding tissues. The scans typically are produced by computed tomography (CT scan), magnetic resonance imaging (MRI), or positron emission tomography (PET scan). Image-guidance technology enables your team to view the tumor and its position in your body before and during each treatment.
IMRT, or intensity modulated radiation therapy with image-guidance, is a commonly performed radiation treatment technique. This technique uses the 3-D scans of your body to guide the beams of radiation to the tumor from many different angles. At each of these angles, the intensity of the radiation is varied (modulated) and the shape changed to suit the shape of the tumor. This directs the prescribed amount of radiation to each part of the tumor, and minimizes exposure to the surrounding healthy tissue. Treatments are typically given up to five treatment times per week over a period of four to six weeks. Each session typically takes from 5 to 20 minutes. Talk to your oncologist about what you may expect with respect to your schedule.
VMAT, or volumetric modulated arc therapy, is an advanced form of IMRT that was introduced in 2007. VMAT uses special software and an advanced linear accelerator to deliver IMRT treatments up to eight times faster than what was previously possible. Unlike conventional IMRT treatments, during which the machine must rotate several times around the patient or make repeated stops and starts to treat the tumor from a number of different angles, VMAT can deliver the dose to the entire tumor in a single rotation—in less than two minutes.
Internal Radiation Therapy - Brachytherapy
Brachytherapy (from the Greek, "brachy" meaning "close") is used infrequently for head and neck cancers, although it is sometimes used to treat tumors in the oral cavity and oropharynx, which is the part of throat that includes the back third of the tongue, soft palate, and tonsils.
Instead of projecting the radiation beam from outside the body, a radioactive substance, sometimes called a "seed," is placed inside the patient with a needle or catheter. The treatment session may last for a few minutes and then the seed is removed. Upon removal, no radioactivity remains in the body. This type of therapy may be repeated every day for a week. Many patients undergoing brachytherapy also receive several sessions of external beam radiation therapy. Talk to your oncologist about his or her treatment recommendation.
*source: National Cancer Institute, 2005
