Radiation therapy for cancer: What to expect during treatment

Learn about radiation therapy — what it is, why and how it's used, and what you can expect — so you'll feel more comfortable with your cancer treatment.

Radiation therapy — also called radiotherapy or X-ray therapy — involves treating cancer with beams of high-energy particles, or waves (radiation), such as gamma rays or X-rays. Radiation therapy damages cells by destroying the genetic material that controls how cells grow and divide. And while both healthy and cancerous cells are damaged by radiation therapy, the goal of treatment is to destroy as few normal, healthy cells as possible.

Who is radiation therapy for?

About half of all people with cancer receive radiation therapy as part of their cancer treatment. Doctors use radiation therapy to treat just about every type of cancer. Radiation therapy is also useful in treating some noncancerous (benign) tumors.

There are several types of radiation therapy. They include:

External beam radiation, the most common type of radiation therapy, this uses radiation that comes from a machine outside your body.
Internal radiation (brachytherapy), in which the radiation comes from small, radioactive pellets placed within your body.
Radiation during surgery (intraoperative radiation), which involves external beam radiation focused directly at the area that needs radiation during an operation.
Systemic radiation, which involves a radioactive substance that can be injected into a vein. The substance travels throughout the body, delivering radiation.

Your doctor may suggest radiation therapy as an option at different times during your cancer treatment and for different reasons, including:

Before surgery, to shrink a cancerous tumor (neoadjuvant therapy)
After surgery, to stop the growth of any remaining cancer cells (adjuvant therapy)
In combination with other treatments, such as chemotherapy, to destroy cancer cells
In advanced cancer to alleviate symptoms caused by the cancer

How do you prepare for radiation therapy?

Before you undergo external beam radiation therapy, your health care team guides you through a planning process that's done to ensure that radiation reaches the precise spot in your body where it's needed. Planning typically includes:

Radiation simulation. During simulation your radiation therapy team works with you to find a comfortable position for you during treatment. It's imperative that you lie still during treatment, so finding a comfortable position is vital. To do this, you'll lie on the same type of table that's used during radiation therapy. Cushions and restraints are used to position you in the right way and to help you hold still. Your radiation therapy team will mark the area of your body that will receive the radiation. Depending on your situation, you may receive temporary marking with a marker or you may receive permanent tattoos.
Planning scans. Your radiation therapy team may have you undergo X-rays or computerized tomography (CT) scans to determine the area of your body to be treated.

After the planning process, you may wait several days before beginning radiation therapy. During this time your radiation therapy team decides what type of radiation you'll receive and what dose you'll receive based on your type and stage of cancer, your general health and your goals for treatment.

How is radiation therapy done?

External beam radiation therapy is conducted using a linear accelerator — a machine that directs high-energy beams of radiation into your body. As you lie on a table, the linear accelerator moves around you to deliver radiation from several angles. The linear accelerator can be adjusted for your particular situation so that it delivers the precise dose of radiation your doctor has ordered.

External beam radiation uses a variety of energy sources, including photons, such as X-rays and gamma rays, and particle beams, such as electrons, protons and neutrons. Each differs in the type of energy emitted, the amount of area it covers and how deeply it penetrates your body. Depending on your type of cancer, your radiation oncologist — a doctor who specializes in treating cancer with radiation — will choose the type of energy best suited for your treatment.

What can you expect during radiation therapy?

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External beam radiation therapy

You typically receive external beam radiation on an outpatient basis about five days a week over a period of one to eight weeks or more. Treatments are usually spread out over several weeks to allow your healthy cells to recover in between radiation therapy sessions. In some cases, a single treatment may be used to help relieve pain or other symptoms associated with more advanced cancers.

During a treatment session, you'll lie down in the position determined during your radiation simulation session. You might be positioned with molds to hold you in place and with shields to block radiation from reaching certain parts of your body.

The linear accelerator machine may rotate around your body to reach the target from different directions. The machine makes a buzzing sound. You'll lie still and breathe normally during the treatment, which takes only a few minutes. Your radiation therapy team stays nearby in a room with video and audio connections so that you can talk to each other. Speak up if you feel uncomfortable, but you shouldn't feel any pain during your radiation therapy session.

Expect your entire treatment session to last approximately 15 to 30 minutes.

Results

If you're receiving radiation to a tumor, your doctor may have you undergo periodic scans to see how your cancer has responded to radiation therapy. In some cases your cancer may respond to treatment right away. In other cases it may take weeks or months for your cancer to respond. Some people aren't helped by radiation therapy.

Risks

Side effects of radiation therapy greatly depend on which part of your body is being radiated and how much radiation is used. You may experience no side effects, or you may experience several. Most side effects are temporary, can be controlled and generally disappear over time once treatment has ended.

Part of body being treated	Common side effects
Any part	Hair loss at treatment site (sometimes permanent), skin irritation at treatment site, fatigue
Head and neck	Dry mouth, thickened saliva, difficulty swallowing, sore throat, changes in the way food tastes, earaches, sore jaw, nausea
Chest	Difficulty swallowing, cough, shortness of breath
Abdomen	Upset stomach, nausea, diarrhea
Pelvis	Diarrhea, bladder irritation, frequent urination, sexual dysfunction

Some side effects may develop later. For example, in rare circumstances a new cancer (second primary cancer) that's different from the first one treated with radiation may develop years later. Or, in cases in which radiation is given to the chest area, late effects may include scarring of the lungs (pulmonary fibrosis), which can make breathing more difficult, and an increased risk of heart problems. Ask your doctor about potential side effects, both short and long term, immediate and delayed, that may occur after your treatment.

Looking ahead

Researchers continue to develop new methods for delivering radiation therapy, always with the goal of directing a high dose of radiation to the tumor while protecting surrounding tissue. Examples of other methods being studied include:

Drugs that protect healthy cells (radioprotectors). These drugs are designed to protect normal cells from radiation, so higher doses of radiation could be used against cancer cells.
Drugs that make cancer more sensitive to treatment (radiosensitizers). Chemotherapy drugs are often given along with radiation therapy, as many types of chemotherapy drugs make cancer cells more sensitive to radiation therapy. Unfortunately the chemotherapy drugs have their own side effects in addition to the side effects of radiation therapy. Researchers are working to develop drugs that make cancer cells more sensitive to radiation without the additional side effects of chemotherapy.
More focused radiation. New types of radiation machines and computer programs are making it possible to deliver a more targeted beam of radiation to tumors.

Innovations in radiation may be available to you in clinical trials. Talk with your doctor about whether you might qualify for a trial.