Radiation Therapy

Radiotherapy, also called radiation therapy, is the treatment of cancer and other diseases with ionizing radiation. Ionizing radiation deposits energy that injures or destroys cells in the area being treated (the "target tissue") by damaging their genetic material, making it impossible for these cells to continue to grow. Although radiation damages both cancer cells and normal cells, the latter are able to repair themselves and function properly. Radiotherapy may be used to treat localized solid tumors, such as cancers of the skin, tongue, brain, breast, or uterine cervix. It can also be used to treat lymphoma (cancers of the blood-forming cells and lymphatic system, respectively).

One type of radiation therapy commonly used involves photons, "packets" of energy.X-rays were the first form of photon radiation to be used to treat cancer. Depending on the amount of energy they possess, the rays can be used to destroy cancer cells on the surface of or deeper in the body. The higher the energy of the x-ray beam, the deeper the x-rays can go into the target tissue. Linear accelerators and betatrons are machines that produce x-rays of increasingly greater energy. The use of machines to focus radiation (such as x-rays) on a cancer site is called external beam radiotherapy.

Gamma rays are another form of photons used in radiotherapy. Gamma rays are produced spontaneously as certain elements (such as radium, uranium, and cobalt 60) release radiation as they decompose, or decay. Each element decays at a specific rate and gives off energy in the form of gamma rays and other particles. X-rays and gamma rays have the same effect on cancer cells.

Another technique for delivering radiation to cancer cells is to place radioactive implants directly in a tumor or body cavity. This is called internal radiotherapy. (Brachytherapy, interstitial irradiation, and intracavitary irradiation are types of internal radiotherapy.) In this treatment, the radiation dose is concentrated in a small area, and the patient stays in the hospital for a few days. Internal radiotherapy is frequently used for cancers of the tongue, uterus, and cervix.

Several new approaches to radiation therapy are being evaluated to determine their effectiveness in treating cancer. One such technique is intraoperative irradiation, in which a large dose of external radiation is directed at the tumor and surrounding tissue during surgery.

Another investigational approach is particle beam radiation therapy. This type of therapy differs from photon radiotherapy in that it involves the use of fast-moving subatomic particles to treat localized cancers. A very sophisticated machine is needed to produce and accelerate the particles required for this procedure. Some particles (neutrons, pions, and heavy ions) deposit more energy along the path they take through tissue than do x-rays or gamma rays, thus causing more damage to the cells they hit. This type of radiation is often referred to as high linear energy transfer (high LET) radiation.

Scientists also are looking for ways to increase the effectiveness of radiation therapy. Two types of investigational drugs are being studied for their effect on cells undergoing radiation. Radiosensitizers make the tumor cells more likely to be damaged, and radioprotectors protect normal tissues from the effects of radiation. Hyperthermia, the use of heat, is also being studied for its effectiveness in sensitizing tissue to radiation.

Other recent radiotherapy research has focused on the use of radiolabeled antibodies to deliver doses of radiation directly to the cancer site (radioimmunotherapy). Antibodies are highly specific proteins that are made by the body in response to the presence of antigens (substances recognized as foreign by the immune system). Some tumor cells contain specific antigens that trigger the production of tumor-specific antibodies. Large quantities of these antibodies can be made in the laboratory and attached to radioactive substances (a process known as radiolabeling). Once injected into the body, the antibodies actively seek out the cancer cells, which are destroyed by the cell-killing (cytotoxic) action of the radiation. This approach can minimize the risk of radiation damage to healthy cells. The success of this technique will depend upon both the identification of appropriate radioactive substances and determination of the safe and effective dose of radiation that can be delivered in this way.

Radiation therapy may be used alone or in combination with chemotherapy or surgery. Like all forms of cancer treatment, radiation therapy can have side effects. Possible side effects of treatment with radiation include temporary or permanent loss of hair in the area being treated, skin irritation, temporary change in skin color in the treated area, and tiredness. Other side effects are largely dependent on the area of the body that is treated.

White blood cells fight infection. Chemotherapy lowers your white blood cell count, which can lower your resistance to infections. Your cancer care team may recommend certain precautions to avoid infection, such as wearing a surgical mask, not being near people with colds, not eating uncooked foods, and washing your hands thoroughly.

Platelets form blood clots that plug up any cuts or bruises. If your bone marrow cannot make enough platelets, you may bleed too much, even from small cuts. If your platelet count is very low, you will need to be very careful to avoid any cuts or bruises. Even brushing your teeth with a brush that has hard bristles could cause your gums to bleed, so you may need a special toothbrush.

Hair, skin, mouth, and stomach:   Cells in your hair, skin, mouth and gastrointestinal tract (stomach and intestines) can be affected by chemotherapy. This can result in hair loss, sores in your mouth, dry skin, nausea, and vomiting.

Sexuality:  Chemotherapy can affect sexuality in both men and women. Sometimes sexual desire is decreased for a period of time, then returns. Some drugs given during chemotherapy may affect a woman's hormones, triggering hot flashes and dryness of the vagina.

The good news is that there are things you can do to lessen or to get rid of some of these side effects.

You can take some medicines at the same time as your chemotherapy to prevent vomiting or feeling sick to your stomach.

New drugs called growth factors can be given as injections to help the bone marrow recover from chemotherapy, and start making new blood cells.

Transfusions of red blood cells or platelets from blood donors help many people.

Remember that not everyone gets the same chemotherapy drugs. Chemotherapy for some cancers may be much stronger and cause more side effects than other drugs. Also, everybody is different. Your general state of health and fitness will affect how your body reacts to chemotherapy.

You may be able to go on with what you normally do while you are on chemotherapy. You may not have to stop working or be on a special diet. On the other hand, some people need to be in the hospital so that doctors can watch them closely and treat certain side effects. Ask your cancer care team what you'll be able to do while you're being treated.

What are the Possible Effects on My Family?

Cancer isn't contagious, so you can go on being close to family and friends. Having chemotherapy won't "rub off " on anybody else either. Depending on how your body reacts to the treatment drugs, people may not notice you are on chemotherapy at all. If you do get unpleasant side effects, your family and friends can do things to help. When someone asks, "How can I help?" have a few suggestions ready.

You may not feel like eating very much, so ask family members to take turns cooking foods that you feel you can eat.

You might get tired after each treatment and need extra rest. Ask your family to do little jobs for you until you feel better.

Remember that your family cares very much about you and they may feel nervous about your chemotherapy. Let your family and friends know how much their support means to you. Be honest about how you feel. Get into the habit of talking things over with your family and friends so they can share your ups and downs.

There will be times when the people closest to you also feel tired or sad, and you can help them feel better by reminding them how much you value their help.

You and Your Doctor:

Because cancer is different for everyone, your chemotherapy will be planned just for you. Work closely with your doctor to decide what's best for you.

Ask questions: Ask the doctor, nurses, social workers, and other professionals on your team as many questions as you like. They know the most about chemotherapy and how it works.

Come prepared: Write down your questions ahead of time and don't be afraid to say you are confused, or want to ask the same questions over again. Nothing you say will sound "silly" or "strange" to your health care team, because they know you want to understand chemotherapy as much as possible. All patients receiving chemotherapy have questions.

These are some questions you might want to ask:

    What are the usual side effects of the chemotherapy you recommended?

    Is there any way to make these side effects less severe?

    How long do the side effects last? Are any permanent?

    How will this chemotherapy affect my prognosis (outlook) for cure or long-term survival?

Click here to view radiation frequently asked questions

Source: American Cancer Society