RADIATION THERAPY & CANCER
Cancer doctors usually treat cancer with radiation therapy, surgery or medications
including chemotherapy, hormonal therapy and/or biologic therapy, either alone or
in combination.
If your cancer can be treated with radiation, you will be referred to a radiation
oncologist - a doctor who specializes in treating patients with radiation therapy.
Your radiation oncologist will work with your primary doctor and other cancer specialists,
such as surgeons and medical oncologists, to oversee your care. He or she will discuss
the details of your cancer with you, the role of radiation therapy in your overall
treatment plan and what to expect from your treatment.
HOW DOES RADIATION THERAPY WORK?
Radiation therapy, or radiotherapy, is the use of various forms of radiation to
safely and effectively treat cancer and other diseases. Radiation oncologists may
use radiation to cure cancer, to control the growth of the cancer or to relieve
symptoms, such as pain. Radiation therapy works by damaging cells. Normal cells
are able to repair themselves, whereas cancer cells cannot. New techniques also
allow doctors to better target the radiation to protect healthy cells.
Sometimes radiation therapy is the only treatment a patient needs. At other times,
it is only one part of a patient's treatment. For example, prostate and larynx cancer
are often treated with radiotherapy alone, while a woman with breast cancer may
be treated with surgery, radiation therapy and chemotherapy.
Radiation may also be used to make your primary treatment more effective. For example,
you can be treated with radiation therapy before surgery to help shrink the cancer
and allow less extensive surgery than would otherwise be needed; or you may be treated
with radiation after surgery to destroy small amounts of cancer that may have been
left behind.
MEETING WITH A RADIATION ONCOLOGIST
If you are considering radiation therapy, you must first meet with a radiation oncologist
to see if radiation therapy is right for you. During your first visit, your doctor
will evaluate your need for radiation therapy and its likely results. This includes
reviewing your current medical problems, past medical history, past surgical history,
family history, medications, allergies and lifestyle. The doctor will also perform
a physical exam to assess the extent of your disease and judge your general physical
condition. You may also be seen by a medical student, a resident (radiation oncologist
in training), a nurse practitioner, a physician's assistant or a nurse.
After reviewing your medical tests, including CT scans, MRI scans and PET scans,
and completing a thorough examination, your radiation oncologist will discuss with
you the potential benefits and risks of radiation therapy and answer your questions.
For a list of questions that you may want to ask, please see the section'What Questions
Should I Ask My Doctor?'
SIMULATION
To be most effective, radiation therapy must be aimed precisely at the same target
or targets each and every time treatment is given. The process of measuring your
body and marking your skin to help your team direct the beams of radiation safely
and exactly to their intended locations is called simulation.
During simulation, your radiation oncologist and radiation therapist place you on
the simulation machine in the exact position you will be in during the actual treatment.
Your radiation therapist, under your doctor's supervision, then marks the area to
be treated directly on your skin or on immobilization devices.
Immobilization devices are molds, casts, headrests or other devices that help you
remain in the same position during the entire treatment. The radiation therapist
marks your skin and/or the immobilization devices either with a bright, temporary
paint or a set of small, permanent tattoos. Your radiation oncologist may request
that special blocks or shields be made for you. These blocks or shields are put
in the external beam therapy machine before each of your treatments and are used
to shape the radiation to your tumor and keep the rays from hitting normal tissue.
Multileaf collimators may also be used to shape the beam and achieve safe delivery
of your radiation treatment.
TREATMENT PLANNING
Once you have finished with the simulation, your radiation oncologist and other
members of the treatment team review the information they obtained during simulation
along with your previous medical tests to develop a treatment plan. Often, a special
treatment planning CT scan is done to help with the simulation and treatment planning.
This CT scan is in addition to your diagnostic CT scan. Frequently, sophisticated
treatment-planning computer software is used to help design the best possible treatment
plan. After reviewing all of this information, your doctor will write a prescription
that outlines exactly how much radiation you will receive and to what parts of your
body.
DURING TREATMENT
EXTERNAL BEAM RADIATION THERAPY TREATMENTS
When you undergo external beam radiation therapy treatment, each session is painless,
just like getting an X-ray. The radiation is directed at your tumor from a machine
located away from your body, usually a linear accelerator. External beam radiation
is noninvasive, unlike surgery which is an invasive process. One of the benefits
of radiation therapy is that it is usually given as a series of outpatient treatments
(meaning you don't have to stay in the hospital). You may not need to miss work
or experience the type of recuperation period that may follow other treatments.
Treatments are usually scheduled five days a week, Monday through Friday, and continue
for one to ten weeks. The number of radiation treatments you will need depends on
the size, location and type of cancer you have, the intent of the treatment, your
general health and other medical treatments you may be receiving.
The radiation therapist will administer you your external beam treatment following
your radiation oncologist's instructions. It will take five to 15 minutes for you
to be positioned for treatment and for the equipment to be set up. If an immobilization
device was made during simulation, it will be used during every treatment to make
sure that you are in the exact same position every day.
Once you are positioned correctly, the therapist will leave the room and go into
the control room next door to closely monitor you on a television screen while giving
the radiation. There is a microphone in the treatment room so you can always talk
with the therapist if you have any concerns. The machine can be stopped at any time
if you are feeling sick or uncomfortable.
The radiation therapist may move the treatment machine and treatment table to target
the radiation beam to the exact area of the tumor. The machine might make noises
during treatment that sound like clicking, knocking or whirring, but do not worry
because the radiation therapist is in complete control of the machine at all times.
The radiation therapy team carefully aims the radiation in order to reduce the dose
to the normal tissue surrounding the tumor. Still, radiation will affect some healthy
cells. Time between daily treatments allows your healthy cells to repair much of
the radiation effect, while cancer cells are not as likely to survive the changes.
Sometimes a course of treatment is interrupted for a day or more. This may happen
if you develop side effects that require a break in treatment. These missed treatments
may be made up by adding treatments at the end. Try to arrive on time and not miss
any of your appointments. Time spent in the treatment room may vary depending on
the type of radiation, but it generally ranges from 10 to 40 minutes. Most patients
are treated on an outpatient basis, and many can continue with normal daily activities.
Your radiation oncologist monitors your daily treatment and may alter your radiation
dose based on these observations. Also, your doctor may order blood tests, X-rays
and other tests to see how your body is responding to treatment. If the tumor shrinks
significantly, another simulation may be required. This allows your radiation oncologist
to change the treatment to destroy the rest of the tumor and spare even more normal
tissue.
WEEKLY STATUS CHECKS
During radiation therapy, your radiation oncologist and nurse will see you regularly
to follow your progress, evaluate whether you are having any side effects, recommend
treatments for those side effects (such as medication), and address any concerns
you may have. As treatment progresses, your doctor may make changes in the schedule
or treatment plan depending on your response or reaction to the therapy.
Your radiation therapy team may meet on a regular basis with other healthcare professionals
to review your case to ensure your treatment is proceeding as planned. During these
sessions, all the members of the team discuss your progress as well as any concerns.
WEEKLY BEAM FILMS
During your course of treatment, correct positions of the treatment beams will be
regularly verified with images made using the treatment beam. These images (called
port films, beam films or portal verification) represent an important quality assurance
check, but do not evaluate the tumor itself.
AFTER TREATMENT
FOLLOW UP
After treatment is completed, follow-up appointments will be scheduled so that your
radiation oncologist can make sure your recovery is proceeding normally and can
continue to monitor your health status. Your radiation oncologist may also order
additional diagnostic tests. Reports on your treatment may also be sent to the other
doctors helping treat your cancer.
As time goes by, the number of times you need to visit your radiation oncologist
will decrease. However, you should know that your radiation oncology team will always
be available should you need to speak to someone about your treatment.
ARE THERE ANY SIDE EFFECTS?
Radiation therapy is usually well tolerated and many patients are able to continue
their normal routines. However, some patients may eventually develop painful side
effects. Be sure to talk to a member of your radiation oncology treatment team about
any problems or discomfort you may have.
Many of the side effects of radiation therapy are only in the area being treated.
For example, a breast cancer patient may notice skin irritation, like a mild to
moderate sunburn, while a patient with cancer in the mouth may have soreness when
swallowing. Some patients who are having their midsection treated may report feeling
sick to their stomach. These side effects are usually temporary and can be treated
by your doctor or other members of the treatment team.
Side effects usually begin by the second or third week of treatment, and they may
last for several weeks after the final radiation treatment. In rare instances, serious
side effects develop after radiation therapy is finished. Your radiation oncologist
and radiation oncology nurse are the best people to advise you about the side effects
you may experience. Talk with them about any side effects you are having. They can
give you information about how to manage them and may prescribe medicines or changes
in your eating habits to help relieve your discomfort.
The side effect most often reported by patients receiving radiation is fatigue.
The fatigue patients experience is usually not severe, and patients may be able
to continue all or some of their normal daily activities with a reduced schedule.
However, treating cancer often requires considerable mental and physical effort.
Whenever possible, try to take time during your treatment to rest and relax.
Many patients are concerned that radiation therapy will cause another cancer. In
fact, the risk of developing a second tumor because of radiation therapy is very
low. For many patients, radiation therapy can cure your cancer. This benefit far
outweighs the very small risk that the treatment could cause a later cancer. If
you smoke, the most important thing you can do to reduce your risk of a second cancer
is to quit smoking.
HOW SHOULD I CARE FOR MYSELF DURING RADIATION THERAPY?
Get plenty of rest. Many patients experience fatigue during radiation therapy, so
it is important to make sure you are well rested. If possible, ask friends and family
to help out during treatment, by running errands and preparing meals. This will
help you get the rest you need to focus on fighting your cancer.
Follow doctor's orders. In many cases, your doctor will ask you to call if you develop
a fever of 101° or higher. Be sure to read your instructions as far as caring for
yourself during treatment.
Eat a balanced, nutritious diet. A nutritionist, nurse or doctor may work with you
to make sure you are eating the right foods to get the vitamins and minerals you
need. With certain types of radiation, you may need to change your diet to minimize
side effects. You should not attempt to lose weight during radiation therapy since
you need more calories due to your cancer and treatment.
Treat the skin that is exposed to radiation with extra care. The skin in the area
receiving treatment may become red and sensitive, similar to getting a sunburn.
Your radiation oncology nurse will review specific instructions for caring for your
skin. Some guidelines include:
- Clean the skin daily with warm water and a mild soap recommended by your nurse.
- Avoid using any lotions, perfumes, deodorants or powders in the treatment area unless approved by your doctor or nurse. Try not to use products containing alcohol and perfumes.
- Avoid putting anything hot or cold on the treated skin. This includes heating pads and ice packs.
- Stay out of the sun. If you must spend time outdoors, wear a hat or clothing to protect your skin. After treat-ment, use sunscreen with an SPF of at least 15.
Seek out support. There are many emotional demands that you must cope with during
your cancer diagnosis and treatment. It is common to feel anxious, depressed, afraid
or hopeless. It may help to talk about your feelings with a close friend, family
member, nurse, social worker or psychologist. To find a support group in your area,
ask your radiation oncology nurse. There are many support groups that meet in person,
over the phone or on the Internet.
TYPES OF RADIATION THERAPY
EXTERNAL BEAM RADIATION THERAPY
During external beam radiation therapy, a beam of radiation is directed through
the skin to the cancer and the immediate surrounding area in order to destroy the
main tumor and any nearby cancer cells. To minimize side effects, the treatments
are typically given five days a week, Monday through Friday, for a number of weeks.
This allows doctors to get enough radiation into the body to kill the cancer while
giving healthy cells time each day to recover.
The radiation beam is usually generated by a machine called a linear accelerator.
The linear accelerator, or linac, is capable of producing high-energy X-rays and
electrons for the treatment of your cancer. Using high-tech treatment planning software,
your treatment team controls the size and shape of the beam, as well as how it is
directed at your body, to effectively treat your tumor while sparing the surrounding
normal tissue.
Several special types of external beam therapy are discussed in the next sections.
These are used for specific types of cancer, and your radiation oncologist will
recommend one of these treatments if he or she believes it will help you.
THREE-DIMENSIONAL CONFORMAL RADIATION THERAPY (3D-CRT)
Tumors are not regular - they come in different shapes and sizes. Three-dimensional
conformal radiation therapy, or 3D-CRT, uses computers and special imaging techniques
to show the size, shape and location of the tumor. Computer assisted tomography
(CT or CAT scans), magnetic resonance imaqinq (MP or MRI scans) and/or positron
emission tomography (PET scans) are used to create detailed, three-dimensional representations
of the tumor and surrounding organs. Your radiation oncologist can then precisely
tailor the radiation beams to the size and shape of your tumor with multileaf collimators
(see picture, right) or custom fabricated field shaping blocks. Because the radiation
beams are very precisely directed, nearby normal tissue receives less radiation
and is able to heal quickly.
INTENSITY MODULATED RADIATION THERAPY (IMRT)
Intensity modulated radiation therapy, or IMRT, is a specialized form of 3D-CRT
that allows radiation to be more exactly shaped to fit the tumor. With IMRT, the
radiation beam can be broken up into many "beamlets," and the intensity of each
beamlet can be adjusted individually. Using IMRT, it may be possible to further
limit the amount of radiation that is received by healthy tissue near the tumor.
In some situations, this may also allow a higher dose of radiation to be delivered
to the tumor, potentially increasing the chance of a cure.
PROTON BEAM THERAPY
Proton beam therapy is a form of external beam radiation treatment that uses protons
rather than X-rays to treat certain types of cancer and other diseases. The physical
characteristics of the proton therapy beam allow doctors to more effectively reduce
the radiation dose to nearby healthy tissue. Proton therapy is available at only
a few specialized centers in the country.
NEUTRON BEAM THERAPY
Like proton therapy, neutron beam therapy is a specialized form of external beam
radiation therapy. It is often used to treat certain tumors that are radioresistant,
meaning that they are very difficult to kill using conventional X-ray radiation
therapy. Neutrons have a greater biologic impact on cells than other types of radiation.
Used carefully, this added impact can be an advantage in certain situations. Neutron
therapy is available at only a few specialized centers.
IMAGE-GUIDED RADIATION THERAPY (IGRT)
Radiation oncologists use image-guided radiation therapy, or IGRT, to help better
deliver the radiation to the cancer since tumors can move between treatments due
to differences in organ filling or movements while breathing. IGRT involves conformal
radiation treatment guided by imaging, such as CT, ultrasound or X-rays, taken in
the treatment room just before the patient is given the radiation treatment. All
patients first undergo a CT scan as part of the planning process. The imaging information
from the CT scan is then transmitted to a computer in the treatment room to allow
doctors to compare the earlier image with the images taken just before treatment.
During IGRT, doctors compare these images to see if the treatment needs to be adjusted.
This allows doctors to better target the cancer while avoiding nearby healthy tissue.
In some cases, doctors will implant a tiny marker in or near the tumor to pinpoint
it for IGRT.
BRACHYTHERAPY
Also known as internal radiation, brachytherapy involves placing radioactive material
into a tumor or its surrounding tissue. Because the radiation sources are placed
so close to the tumor, your radiation oncologist can deliver a large dose of radiation
directly to the cancer cells. The word brachytherapy comes from the Greek"brachy°meaning
short distance. During brachytherapy, the radioactive sources may be left in place
permanently or only temporarily, depending upon your cancer. To position the sources
accurately, special catheters or applicators are used. There are two main types
of brachytherapy - intracavitary treatment and interstitial treatment. With intracavitary
treatment, the radioactive sources are put into a space near where the tumor is
located, such as the cervix, the vagina or the windpipe. With interstitial treatment,
the radioactive sources are put directly into the tissues, such as the prostate.
The radioactive sources used in brachytherapy, such as thin wires, ribbons, capsules
or seeds, come in small sealed containers. These sources may be implanted permanently
or temporarily. A permanent implant remains in the body after the sources are no
longer radioactive. Other radioactive sources are placed temporarily inside the
body and are removed after the right amount of radiation has been delivered. Sometimes
these procedures require anesthesia and a brief stay in the hospital. Patients with
permanent implants may have a few restrictions at first and then can quickly return
to their normal activities. Temporary implants are left inside of your body for
several hours or days. While the sources are in place, you will stay in a private
room. Doctors, nurses and other medical staff will continue to take care of you,
but they will take special precautions to limit their exposure to radiation. Devices
called high-dose-rate remote after loading machines allow radiation oncologists
to complete brachytherapy quickly, in about 10 to 20 minutes. Powerful radioactive
sources travel through small tubes called catheters to the tumor for the amount
of time prescribed by your radiation oncologist. You may be able to go home shortly
after the procedure. Depending on the area treated, you may receive several treatments
over a number of days or weeks. Most patients feel little discomfort during brachytherapy.
If the radioactive source is held in place with an applicator, you may feel discomfort
from the applicator. There are medications that can relieve this discomfort. If
you feel weak or queasy from the anesthesia, your radiation oncologist can give
you medication to make you feel better. Depending on the type of brachytherapy you
received, you may need to take some precautions after you leave your treatment,
particularly if you plan to be around young children or pregnant women. Ask your
radiation oncologist or radiation oncology nurse about anything special you should
know.
IMRT
Intensity modulated radiation therapy (IMRT) is a revolutionary type of external
beam treatment that is able to conform radiation to the size, shape and location
of a tumor. It involves varying (or modulating) the intensity of the radiation beam.
IMRT compared to conventional radiation The effectiveness of conventional radiation
therapy is limited by imperfect targeting of tumors and insufficient radiation dosing.
Because of these limitations, conventional radiation can expose healthy tissue to
radiation, causing complications. With IMRT, the optimal dose of radiation is delivered
to the tumor and dose to surrounding healthy tissue is minimized. Preliminary clinical
studies indicate that higher radiation dose delivered with IMRT techniques are improving
the rate of local tumor control.
IMRT patient benefits
• IMRT allows for more precise tumor targeting which allows physician to increase
the dose to the tumor. • Higher doses made possible by IMRT are more likely to control
the tumor and prevent recurrence. • IMRT results in less doses to surrounding healthy
tissue and organs reducing the complication rate. • IMRT can treat odd-shaped tumors,
or tumors wrapped around or near critical structures. • IMRT is used to treat patients
with tumors of the prostate, breast and head and neck region.
BAT B-MODE ACQUISITION AND TARGETING SYSTEM
BAT is an ultrasound-based stereotactic tumor localization device designed to maximize
the precision and effectiveness of external beam radiation therapy. Ultrasound is
ideal r for localizing the prostate gland on a daily basis for IMRT. Safe and compatible
BAT is the first of its kind: a system that tracks tumor location and allows physicians
to more precisely position the patient in alignment with the treatment plan. BAT
offers the benefits of:
- Reduced target uncertainty- from 2cm to 2mm
- Safer dose escalation - increases confidence for field positioning
- Ultrasound-based technology - provides safe, non-invasive imaging
Useful for any soft tissue structure
Though originally developed to localize prostate tumors, BAT is considered a valuable
tool for many kinds of radiation treatment, including cancers of the breast, bladder,
liver, pancreas and neck.
HIGH DOSE RATE (HDR) BRACHYTHERAPY/MAMMOSITE® RADIATION THERAPY SYSTEM
Offer the benefit of Breast conservation Therapy (BCT) to more patients. Ideal for
partial breast irradiation, the Mammosite® Radiation System (RTS) is a balloon catheter
brachytherapy device (pictured left) used to deliver a highly conformal dose to
the tissue surrounding the lumpectomy cavity, where tumors are more likely to recur.
Advantages:
- Treatment time of 5 days compared to 6 weeks with conventional therapy.
- A precise dose of radiation is delivered to the tissue surrounding the resection cavity, as opposed to treating the whole breast.
- Minimizes radiation exposure to healthy tissue. Radiation therapy - simplified
- Creates treatment geometry that is easily identifiable and reproducible
- Easy insertion and removal of catheter
- Performed as an outpatient procedure
Our HDR unit is currently capable of treating cancers of the breast and gynecological
sites. For additional information, ask your doctor or visit the MammoSite RTS website
at www.mammosite.com
ADDITIONAL TREATMENT OPTIONS SYSTEMIC RADIATION THERAPY
Certain cancers may be treated by swallowing radioactive pills or receiving radioactive
fluids in the vein (intravenous). This type of treatment is called systemic radiation
therapy because the medicine goes to the entire body. For example, radioactive iodine
(1-131) capsules are given to treat some types of thyroid cancer. Another example
is the use of intravenous radioactive material to treat pain due to cancer that
has spread to the bone. Radiolabeled antibodies are monoclonal antibodies with radioactive
particles attached. These antibodies are designed to attach themselves directly
to the cancer cell and damage it with small amounts of radiation.
NOVEL TARGETED THERAPIES
Cancer doctors now know much more about how cancer cells function. New cancer therapies
use this information to target cancer cell functions and stop them. Called targeted
therapies, they can be more specific in stopping cancer cells from growing and may
make other treatments work better. For example, some medicines work to prevent cancers
from growing by preventing the growth of new blood vessels that would nourish the
cancer. Other targeted therapies work more directly on cancer cells by blocking
the action of molecules on the surface of cancer cells called growth factors.
RADIOSENSITIZERS
Any drug that can make tumor cells more sensitive to radiation is called a radiosensitizer.
Combining radiation with radiosensitizers may allow doctors to kill more tumor cells.
Some types of chemotherapy and some novel targeted therapies can act as radiosensitizers.
RADIOPROTECTORS
Some medicines called radioprotectors can help protect healthy tissue from the effects
of radiation.
INTRAOPERATIVE RADIATION THERAPY
Radiation therapy given during surgery is called intraoperative radiation therapy.
Intraoperative radiation therapy is helpful when vital normal organs are too close
to the tumor. During an operation, a surgeon temporarily moves the normal organs
out of the way so radiation can be applied directly to the tumor. This allows your
radiation oncologist to avoid exposing those organs to radiation. Intraoperative
radiation can be given as external beam therapy or as brachytherapy.