Radiation therapy (sometimes called radiotherapy, x-ray therapy, or irradiation)
is the treatment of disease using penetrating beams of high energy waves or streams of particles called radiation.
Many years ago doctors learned how to use this energy to "see"
inside the body and find disease. You've probably seen a chest x-ray or x-ray pictures of your teeth or your bones. At high
doses (many times those used for x-ray exams) radiation is used to treat cancer and other illnesses.
The radiation used for cancer treatment comes from special
machines or from radioactive substances. Radiation therapy equipment aims specific amounts
of the radiation at tumors or areas of the body where there is disease.
Radiation in high
doses kills cells or keeps them from growing and dividing. Because cancer cells grow and divide more rapidly than most of
the normal cells around them, radiation therapy can successfully treat many kinds of cancer. Normal cells are also affected
by radiation but, unlike cancer cells, most of them recover from the effects of radiation.
To protect normal cells, doctors carefully limit the doses
of radiation and spread the treatment out over time. They also shield as much normal tissue as possible while they aim the
radiation at the site of the cancer.
The goal of radiation therapy is to kill the cancer cells with
as little risk as possible to normal cells. Radiation therapy can be used to treat many kinds of cancer in almost any part
of the body. In fact, more than half of all people with cancer are treated with some form of radiation. For many cancer patients,
radiation is the only kind of treatment they need. Thousands of people who have had radiation therapy alone or in combination
with other types of cancer treatment are free of cancer.
Radiation treatment, like surgery, is a local treatment —
it affects the cancer cells only in a specific area of the body. Sometimes doctors add radiation therapy to treatments that
reach all parts of the body (systemic treatment) such as chemotherapy, or biological therapy to improve treatment results. You may hear your doctor use the
term, adjuvant therapy , for a treatment that is added to, and given after, the primary
Radiation therapy is often used with surgery to treat cancer.
Doctors may use radiation before surgery to shrink a tumor. This makes it easier to remove the cancerous tissue and may allow
the surgeon to perform less radical surgery.
Radiation therapy may be used after surgery to stop the growth
of cancer cells that may remain. Your doctor may choose to use radiation therapy and surgery at the same time. This procedure,
known as , is explained more fully in the "External Radiation Therapy section."
In some cases, instead of surgery, doctors use radiation along
with anticancer drugs (chemotherapy) to destroy the cancer. Radiation may be given before, during, or after chemotherapy.
Doctors carefully tailor this combination treatment to each patient's needs depending on the type of cancer, its location,
and its size. The purpose of radiation treatment before or during chemotherapy is to make the tumor smaller and thus improve
the effectiveness of the anticancer drugs. Doctors sometimes recommend that a patient complete chemotherapy and then have
radiation treatment to kill any cancer cells that might remain. When curing the cancer is not possible, radiation therapy can
be used to shrink tumors and reduce pressure, pain, and other symptoms of cancer. This is called palliative care or palliation. Many cancer patients find that they have a better
quality of life when radiation is used for this purpose.
The brief high doses of radiation that damage or destroy cancer
cells can also injure or kill normal cells. These effects of radiation on normal cells cause treatment side effects. Most
side effects of radiation treatment are well known and, with the help of your doctor and nurse, easily treated. The side effects
of radiation therapy and what to do about them are discussed in the Managing Side Effects section.
The risk of side effects is usually less than the benefit of
killing cancer cells. Your doctor will not advise you to have any treatment unless the benefits -- control of disease and
relief from symptoms -- are greater than the known risks.
Radiation therapy can be given in one of two ways: external
or internal. Some patients have both, one after the other.
Most people who receive radiation therapy for cancer have external radiation . It is usually given during outpatient visits to a hospital
or treatment center. In external radiation therapy, a machine directs the high-energy rays at the cancer and a small margin
of normal tissue surrounding it.
The various machines used for external radiation work in slightly
different ways. Some are better for treating cancers near the skin surface; others work best on cancers deeper in the body.
The most common type of machine used for radiation therapy is called a linear accelerator . Some radiation machines use a variety of radioactive substances
(such as cobalt-60, for example) as the source of high-energy rays. Your doctor decides which type of radiation therapy machine
is best for you. You will find more information about external radiation in the next chapter.
When internal radiation therapy is used, the radiation source is placed inside the body.
This method of radiation treatment is called brachytherapy or implant therapy. The source of the radiation (such as radioactive
iodine, for example) sealed in a small holder is called an implant . Implants may be thin wires, plastic tubes (catheters), capsules,
or seeds. An implant may be placed directly into a tumor or inserted into a body cavity. Sometimes, after a tumor has been
removed by surgery, the implant is placed in the 'tumor bed' (the area from which the tumor was removed) to kill any tumor
cells that may remain.
Another type of internal radiation therapy uses unsealed radioactive
materials which may be taken by mouth or injected into the body. If you have this type of treatment, you may need to stay
in the hospital for several days. See the internal radiation therapy section for more information.
A doctor who specializes in using radiation to treat cancer
— a radiation oncologist — will prescribe the type and amount of treatment that
is right for you. The radiation oncologist is the person referred to as "your doctor" throughout this booklet. The radiation
oncologist works closely with the other doctors and health care professionals involved in your care. This highly trained health
care team may include:
- The radiation physicist, who makes sure that the equipment is working properly and that
the machines deliver the right dose of radiation. The physicist also works closely with your doctor to plan your treatment.
- The dosimetrist, who works under the direction of your doctor and the radiation
physicist and helps carry out your treatment plan by calculating the amount of radiation to be delivered to the cancer and
normal tissues that are nearby.
- The radiation therapist, who positions you for your treatments and runs the equipment
that delivers the radiation.
- The radiation nurse, who will coordinate your care, help you learn about treatment,
and tell you how to manage side effects. The nurse can also answer questions you or family members may have about your treatment.
Your health care team also may include a physician assistant,
radiologist, dietitian, radiation oncologist, physical therapist, social worker, or other health care professional.
Treatment of cancer with radiation can be costly. It requires
very complex equipment and the services of many health care professionals. The exact cost of your radiation therapy will depend
on the type and number of treatments you need.
Most health insurance policies, including Part B of Medicare,
cover charges for radiation therapy. It's a good idea to talk with your doctor's office staff or the hospital business office
about your policy and how expected costs will be paid.
In some states, the Medicaid program may help you pay for treatments.
You can find out from the office that handles social services in your city or county whether you are eligible for Medicaid
and whether your radiation therapy is a covered expense.
If you need financial aid, contact the hospital social service
office or the National Cancer Institute's (NCI) Cancer Information Service at 1-800-4-CANCER. They may be able to direct you
to sources of help. Additional sources of cancer information are described in the resources sectionRadiation Therapy