Radiation in Cancer
Is Radiation Therapy?
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
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.
How Does Radiation Therapy Work?
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
What Are the Goals and Benefits of Radiation
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
intraoperative radiation, is explained more fully
in this booklet in Section 2, "External Radiation
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.
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.
What Are the Risks of Radiation Therapy?
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 Section 4 of this booklet, "Managing
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.
How Is Radiation Therapy Given?
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
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. More information about internal
radiation therapy can be found in Section 3.
Who Gives Radiation Treatments?
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
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
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 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
Your health care team also may include a physician
assistant, radiologist, dietitian, physical
therapist, social worker, or other health care
Is Radiation Treatment Expensive?
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 section at
the end of this book.