Radiation Therapy

Radiation therapy has come a long way since its beginnings in the late 1800's, shortly after the discovery of the x-ray. (Read about "X-rays") Today more than 60 percent of all cancer patients receive some form of radiation therapy during the course of their treatment, according to the American College of Radiology (ACR). (Read about "Cancer Treatments") Radiation therapy may be used to cure cancer, alleviate symptoms of cancer or even manage pain associated with cancer, according to ACR. Your physician may have prescribed radiation as a course of treatment for you either alone or combined with chemotherapy.

What it is

If you have ever had an x-ray, then you have experienced some radiation. Radiation therapy uses a higher energy radiation to kill cancer cells. Cancer starts when a normal healthy cell in your body, one of trillions, becomes a cancer cell. (Read about "Cancer: What It Is") The cancer cell grows making more cancer cells. If left untreated, it can spread, according to the American Cancer Society, (ACS). Radiation keeps the cancer cells from growing and multiplying. While normal cells can be damaged by the therapy, ACA says they can repair themselves. Cancer cells cannot be repaired.

Radiation therapy cannot always cure cancer. Often it may be used to slow the growth of a tumor, to prolong life or help you feel better, according to ACS. It's important that you and your doctor discuss the goal of your therapy. Radiation may be given before, during or after surgery, depending on the type of cancer being treated. Sometimes it can be given alone, without surgery or other treatments.

Types of radiation therapy

Depending on the type, size and location of the cancer you have, your physician may use one or a combination of three types of radiation therapy: external, internal or systemic, according to ACS. You can read more about each of these below.

External radiation - Radiation that comes from a source outside the body is called external beam radiation. This radiation sends high energy doses of radiation to the tumor and possible an area around the tumor. It will be up to your doctor to decide how many treatments you need. Treatments are typically given 5 days a week for 1 to 10 weeks. For many people, this is a painless procedure that will take just a few minutes. This form of radiation does not make a person radioactive.

According to the National Cancer Institute (NCI), patients usually receive external-beam radiation therapy in daily treatment sessions over the course of several weeks. The number of treatment sessions depends on many factors, including the total radiation dose that will be given.

One of the most common types of external-beam radiation therapy, according to NCI, is called 3-dimensional conformal radiation therapy (3D-CRT). 3D-CRT uses very sophisticated computer software and advanced treatment machines to deliver radiation to very precisely shaped target areas.

Many other methods of external-beam radiation therapy are currently being tested and used in cancer treatment. These methods include:

• Intensity-modulated radiation therapy (IMRT) - IMRT uses hundreds of tiny radiation beam-shaping devices, called collimators, to deliver a single dose of radiation. The collimators can be stationary or can move during treatment, allowing the intensity of the radiation beams to change during treatment sessions. This kind of dose modulation allows different areas of a tumor or nearby tissues to receive different doses of radiation. The goal of IMRT is to increase the radiation dose to the areas that need it and reduce radiation exposure to specific sensitive areas of surrounding normal tissue. Compared with 3D-CRT, IMRT can reduce the risk of some side effects, such as damage to the salivary glands (which can cause dry mouth, or xerostomia), when the head and neck are treated with radiation therapy. (Read about "Oral Health" "Head & Neck Cancers")
• Image-guided radiation therapy (IGRT) - In IGRT, repeated imaging scans (CT, MRI, or PET) are performed during treatment. (Read about "CT Scan - Computerized Tomography" "MRI - Magnetic Resonance Imaging" "PET - Positron Emission Tomography") These imaging scans are processed by computers to identify changes in a tumor's size and location due to treatment and to allow the position of the patient or the planned radiation dose to be adjusted during treatment as needed. Repeated imaging can increase the accuracy of radiation treatment and may allow reductions in the planned volume of tissue to be treated, thereby decreasing the total radiation dose to normal tissue.
• Tomotherapy - Tomotherapy is a type of image-guided IMRT. A tomotherapy machine is a hybrid between a CT imaging scanner and an external-beam radiation therapy machine. The part of the tomotherapy machine that delivers radiation for both imaging and treatment can rotate completely around the patient in the same manner as a normal CT scanner. Tomotherapy machines can capture CT images of the patient's tumor immediately before treatment sessions, to allow for very precise tumor targeting and sparing of normal tissue.
• Stereotactic radiosurgery - Stereotactic radiosurgery (SRS) can deliver one or more high doses of radiation to a small tumor. SRS uses extremely accurate image-guided tumor targeting and patient positioning. Therefore, a high dose of radiation can be given without excess damage to normal tissue. SRS can be used to treat only small tumors with well-defined edges. It is most commonly used in the treatment of brain or spinal tumors and brain metastases from other cancer types. (Read about "Brain Tumors") For the treatment of some brain metastases, patients may receive radiation therapy to the entire brain (called whole-brain radiation therapy) in addition to SRS. SRS requires the use of a head frame or other device to immobilize the patient during treatment to ensure that the high dose of radiation is delivered accurately.
• Stereotactic body radiation therapy - Stereotactic body radiation therapy (SBRT) delivers radiation therapy in fewer sessions, using smaller radiation fields and higher doses than 3D-CRT in most cases. By definition, SBRT treats tumors that lie outside the brain and spinal cord. Because these tumors are more likely to move with the normal motion of the body, and therefore cannot be targeted as accurately as tumors within the brain or spine, SBRT is usually given in more than one dose. SBRT can be used to treat only small, isolated tumors, including cancers in the lung and liver. Many doctors refer to SBRT systems by their brand names, such as the CyberKnife.
• Proton therapy - External-beam radiation therapy can be delivered by proton beams as well as the photon beams described above. Protons are a type of charged particle. Proton beams differ from photon beams mainly in the way they deposit energy in living tissue. Whereas photons deposit energy in small packets all along their path through tissue, protons deposit much of their energy at the end of their path (called the Bragg peak) and deposit less energy along the way. The idea is to reduce the exposure of normal tissue to radiation, possibly allowing the delivery of higher doses of radiation to a tumor.
• Other charged particle beams - Electron beams are used to irradiate superficial tumors, such as skin cancer (Read about "Skin Cancer") or tumors near the surface of the body, but they cannot travel very far through tissue. Therefore, they cannot treat tumors deep within the body.

Patients can discuss these different methods of external radiation therapy with their doctors to see if any is appropriate for their type of cancer and if it is available in their community or through a clinical trial. (Read about "Clinical Studies")

Brachytherapy or internal radiation - Sometimes a radiation source is placed inside your body through a needle like tube. This is referred to as internal radiation therapy or brachytherapy. The implant looks like a small seed or pellet, but it can release a large dose of radiation to the cancer cells. It can be left inside forever or just for a short time. The implant will stop giving off radiation after a few weeks or months. If the implant stays in, ACS says it will not cause any harm. Brachytherapy can be given as a low-dose-rate or a high-dose-rate treatment:

• In low-dose-rate treatment, cancer cells receive continuous low-dose radiation from the source over a period of several days.
• In high-dose-rate treatment, a robotic machine attached to delivery tubes placed inside the body guides one or more radioactive sources into or near a tumor, and then removes the sources at the end of each treatment session. High-dose-rate treatment can be given in one or more treatment sessions. An example of a high-dose-rate treatment is the MammoSite system.

Systemic radiation - Radiopharmaceuticals are called systemic radiation and usually come in the form of a liquid. They can be given by either an injection or by mouth. These pharmaceuticals can travel through the body and give off their radiation at the site of the cancer. Since this form of therapy can leave your body through fluids like blood, sweat and saliva, your doctor may recommend safety measures to protect those around you. This may include a hospital stay or limited contact with friends and family.

Side effects

You may not experience side effects from radiation therapy. If you do, there are some that are more common than others. ACS lists the following as common side effects:

• loss of appetite
• skin changes
• fatigue
• nausea

Other side effects may be experienced depending on the location of the treatment. They include:

• hair loss
• cough or sore throat depending if chest area is treated
• sun burned look at location of treatment site

Many of these side effects disappear after treatment ends, but there is a possibility of side effects developing long after radiation therapy. NCI refers to these as late side effects and says they may include:

• infertility (Read about "Infertility")
• memory loss
• damage to the bowels or bladder
• fibrosis, which is scarring of tissue and can cause restricted movement
• rarely, a second form of cancer can be caused by radiation exposure

Whether a patient experiences late side effects may depend on other aspects of their cancer as well as individual risk factors, according to NCI. For example:

• chemotherapy drugs
• age - the risk for a second cancer is highest for children or adolescents being treated for cancer (Read about "Cancer and Children")
• genetics (Read about "Genetics")
• lifestyle - smoking can also increase the risk of late side effects (Read about "Quit Smoking")

Taking care of yourself

It is important that you take proper care of yourself if you are undergoing radiation therapy. Your healthcare provider will give you tips on how to do this, but ACS has some suggestions as well:

• Rest - fatigue can last more than a month after treatment, so make sure you take a break from your normal activities if needed.
• Skin care - clear your skin with mild soap and water that experts say is safe. Do not use any special creams lotions, powders or deodorants without medical approval. (Read about "Skin")
• Eat healthy foods - your healthcare providers may try to work with you to get the right nutrients into your system. Discuss this with your healthcare provider. They may have ideas for your diet that may settle the side affects of sore throat or stomach upset. (Read about "Dietary Guidelines")
• Stay out of the sun as skin in the treatment area will burn more quickly.
• Don't use heating pads or ice packs on treatment sites.
• Wear loose fitting clothing and stay away from starch.
• Try not to rub or scratch your skin.
• Tell your doctor about all medicines and vitamins you are taking. (Read about "Medicine Safety" "Vitamins & Minerals")
• Follow up with your healthcare provider if you notice any new lumps rashes, or pain that gets worse or any other symptoms you find worrisome.

Research

Scientists are researching how to use radiation therapy more safely and effectively, according to NCI. Clinical trials allow experts to compare new treatments with common practices as well as compare side effects. (Read about "Clinical Studies") Here are some of the improvements researchers are looking at, according to NCI:

• real time image-guided radiation
• radiosensitizers which make cancer cells more sensitive to radiation
• radioprotectors which protect normal cells from the effects of radiation therapy
• carbon ion beams may help treat some cancers resistant to radiation therapy