Radiation as Cancer Treatment by:
Michael Guthrie, R. Ph.
About half the people with cancer need or
require radiation therapy as part of their overall treatment plan (Dollinger,
1997). There are three main reasons why radiation is employed. First, it is used
to try and cure the cancer and this is usually a fairly long and complex course.
Second, it is used for palliation (relieve the symptoms). Third, radiation is
used adjunctively, usually after surgery, to prevent recurrence.
interesting that ionizing radiation is both a cause of cancer, and a treatment
for cancer! To put this in perspective, ionizing radiation such as Radon, x-ray,
and other sources is thought to contribute to less than 3 % of all cancers,
partly due to the fact that radiation so effectively kills cells that mutated
cells can’t go on to multiply.
The goal of radiation as cancer treatment
is to destroy rapidly growing cells, such as cancer cells. Radiation is given
either externally, or at a very short distance, even internally. Brachytherapy
is a type of short distance radiation, but the term “brachytherapy” is often
used universally to define this type of radiation.
There are a number of
professionals who get involved when radiation is prescribed. The first is the
radiation oncologist. This is the medical doctor who is in charge of the
patient’s treatment plan, and who monitors for side effects and efficacy of the
radiation. The medical physicist is in charge of maintaining and calibrating the
complex equipment used to deliver the radiation. The radiation therapist is the
one who actually administers the radiation per the radiation oncologist’s
orders. Finally the dosimeterist calculates the doses of radiation at various
points in the body.
Simulation is an important step in radiation
therapy. In the simulation phase the patient actually goes to the radiation
department and lies on under a machine called a simulator. The skin is marked
for future positioning purposes and x-rays are taken. Photographs are often
taken, and sometimes CT scans are performed. All of this is done to assure that
the proper amount of radiation is applied to the exact location desired. After
the simulation, there are meetings between the various team members mentioned
Radiation treatments usually last from 2 to 5 weeks. Each session
only lasts a few minutes and is entirely painless. Usually radiation is given in
numerous smaller doses rather than in few large bursts as this give normal cells
more opportunity to recover.
Side effects of radiation can be bothersome
and can include redness, dryness, itchiness, diarrhea, nausea, vomiting and
changes in blood counts. The actual type of side effect, and the severity is
determined by where the radiation is applied, and how large the dose is. In
almost all cases the side effects go away in a few weeks, but some patients may
experience prolonged side effects.
Currently there are more focused and
sophisticated forms of radiation being used and developed. Some, like the gamma
knife, are being used in certain brain cancers with promising results.
Fortunately these new devices are more focused, and have less side effects than
more antiquated approaches.
Dollinger, Malin (1997). Everyone’s Guide to
Cancer Therapy. Somerville House: Toronto