Radiation Therapy
Radiation therapy is a form of treatment that uses high intensity
x-rays or particles to destroy cancer cells. After surgery to remove the
cancer, x-ray beams are aimed at the breast to destroy any remaining cancer
cells. This treatment is also used to destroy remaining cancer cells in the
axillary (underarm) lymph nodes and, in rare instances, in lymph nodes above
the collarbone and in the chest wall.
Radiation therapy is also sometimes used to reduce the size of
a tumor before surgery and to treat recurrent cancer. Radiation therapy cannot be
used instead of surgery, nor can it be used as a substitute for most drug
treatments. Often, both chemotherapy and radiation treatments are used; chemotherapy
to destroy cancer cells that may have spread throughout the body and radiation
to destroy cancer cells locally (in the breast and axillary areas only).
How Radiation Therapy Works
High doses of radiation can interfere with the cell cycle through which both normal cells and
abnormal cancer cells grow and reproduce to form two new cells. It is thought
to work by damaging the DNA in the cells, making them unable to divide. DNA
(deoxyribonucleic acid) is the part of the cell that carries the genetic
code for the division and growth of cells.
Administration of Radiation Therapy
External Beam Radiation
Radiation
therapy itself is a painless procedure with few side effects, but
it does require daily trips to the hospital for treatment sessions
over a period of six to eight weeks. External beam radiation is
the usual type of treatment for breast cancer. Radiation is focused
from a source outside the body on the site of the cancer. This
procedure is like getting a diagnostic x-ray, but the radiation
is more intense.
Before
radiation treatments start, the physician and his staff will determine
the best angles for aiming the high-energy beam to reach the breast
area, with as little effect on surrounding tissues as possible.
They will then make ink marks on the skin to outline the places
on the body where the beam will be aimed. These markings will be
used at each treatment session to ensure that the radiation beam
is aimed consistently and accurately.
The
full course of treatment usually runs from 6 to 8 weeks, with sessions
from Monday through Friday, and rest and recovery periods during
weekends. Patients are generally advised not to use antiperspirant
or deodorant on the side being treated, because these preparations
contain aluminum that may interfere with the radiation beam. During
the actual exposure, the patient must remain as still as possible.
Each exposure lasts only a few minutes and is completely painless.
Brachytherapy (Internal Radiation)
Brachytherapy,
also known as internal radiation, is a different way of delivering
radiation therapy. This is considered an experimental therapy,
with clinical studies underway to assess its effectiveness. In
this form of breast radiation therapy, radioactive substances are
placed directly into the breast tissue next to the cancer. The
usual treatment course runs one week, versus an average of six
weeks for external beam radiation. Although this therapy has been
used more often for other forms of cancer, its effectiveness as
a breast cancer treatment has not yet been established. Study results
over the next several years should help determine the best use
for this therapy.
Side Effects of Radiation Therapy
Side effects of radiation therapy vary from patient to patient;
some women experience no or mild side effects throughout the course of treatment.
Most side effects are not serious, and disappear quickly.
The most common temporary side effects are:
- Fatigue
- most people experience fatigue after a few weeks of radiation
therapy. It is helpful to limit activities and to plan schedules
so that there is more time for rest.
- Skin
irritation and redness, similar to a sunburn - these symptoms
may develop by the third or fourth week of treatment. Exposure
of the area to sunlight should be avoided, and the use of any
lotions or creams should be discussed with the physician.
- Swelling
and tenderness in breast and chest area - the swelling should
subside after treatment ends, but some women experience a degree
of tenderness for up to a year after treatment.
On a long-term basis, the treated breast may become slightly
smaller or larger. The breast may also become slightly firmer, but significant
hardening is rare.
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