Radiation Therapy for Spinal Tumors

The ultimate goal of radiation therapy is to destroy a spinal tumor. Radiation is also used to shrink a tumor before or after spine surgery and to relieve tumor-related pain.

Radiation therapy employs a multi-disciplinary team approach. Members of your treatment team may include a radiation oncologist, a neuroradiologist, a pathologist, an angiographer (a medical professional who interprets angiograms, x-rays of the blood vessels), a dosimetrist (a specialist who determines how many radiation treatments you'll need and what dose is necessary), and a spine surgeon.

Before radiation therapy is recommended, many things are considered, such as the type of tumor, neurologic deficit, spinal deformity, and bone or spinal cord involvement. The doctor will also consider you general health, symptoms, and life expectancy. A careful and thoughtful assessment is important because there are many types of radiation and delivery methods. Planning is essential to a good radiation therapy outcome.

Sometimes radiation therapy is combined with a radiosensitizer. A radiosensitizer is a drug that makes cancer cells hypersensitive to radiation's effects.

Types of Radiation Therapy
Just as there are many types of spinal tumors, there are many radiation therapies. Your doctor will discuss which one(s), if any, are appropriate for your treatment plan.

• External Radiation Therapy: External radiation therapy is the most common and is delivered to the patient from the outside of the body. In other words, radiation is directed at a specific area of the body or target. This type of therapy is often provided on an outpatient basis.
  
  
• Internal Radiation Therapy (or Interstitial Radiation Therapy): This kind of radiation therapy delivers radiation by means of sealed implants inserted near the tumor. This type of therapy is more common in cases of neck cancer. This therapy usually requires hospitalization because the patient is radioactive. Special precautions are taken to protect hospital staff and visitors.
  
  
• Palliative Radiation Therapy: This is delivered to help reduce pain and symptoms from metastatic cancer (cancer that has spread).
  
  
• Prophylactic Radiation Therapy: This is delivered to cancer-free areas to help prevent the spread (metastasis) of cancer cells. This type of radiation is not suitable for all patients or types of cancerous spinal tumors.

Combining Drugs with Radiation
As mentioned earlier, radiosensitizers are drugs that can help make cancer cells more receptive to the goals of radiation. Sometimes these drugs are called hypoxic radiosensitizers. Basically, these drugs reduce the amount of oxygen (hypoxicity) cancer cells can absorb. Since oxygen is essential to cell repair, hypoxicity contributes to cancer cell death.

To protect non-cancerous cells from radiation's harmful effects, radioprotector drugs may be administered. Currently, the only drug approved by the US Food and Drug Administration (FDA) is amifostine (brand name Ethyol). It is administered intravenously to prevent dry mouth and protect the saliva-producing glands in patients with neck cancer.

Currently, existing drugs are under investigation for other applications in radiation therapy. New drug research is also being conducted.

Details about Radiation Therapy
Simulation is the term used to describe where beams of radiation will be aimed. The radiation therapist uses x-ray or CT to determine the exact target spot(s). Radiation target spots are marked—with a marking pen on your body.

Because you must lie very still during radiation therapy, a body mold may be constructed to keep you comfortably immobile. Such body molds are usually made from foam or plastic. If necessary, radiation shields are built into the body mold to protect organs and tissues.

Side Effects of Radiation Therapy
Most radiation therapy patients experience side effects. Ask your doctor or radiologist about the side effects you may experience. Some common side effects include:

• Skin irritation at the therapy site
• Nausea, vomiting
• Fatigue
• Hair loss

Your doctor can recommend over-the-counter or prescription medication to help you manage the side effects of radiation therapy.

Sources

1. American Association of Medical Dosimetrists (http://www.medicaldosimetry.org/index.cfm)
2. Ryken TC. Brain and Spinal Tumors: Frequently Asked Questions. University of Iowa Healthcare, September 2000. http://www.uihealthcare.com/topics/medicaldepartments/neurosurgery/brainspinaltumors/index.html Accessed October 10, 2008.
3. National Cancer Institute (www.cancer.gov).
4. Radiological Society of North America (http://www.radiologyinfo.org/index.cfm?bhcp=1).