Radiation therapy is a
common cancer treatment option used to shrink the tumor while sparing the maximum neighboring
healthy tissue possible. This is a local treatment whose sensitivity varies depending on the tissue, types of
cells, and patient treated. The Radiotherapy can be used alone or in combination with other therapeutic methods
such as chemotherapy and surgical therapy (surgery). The choice depends on the objective of
the treatment (curative, palliative), which will depend on
the location and stage of the tumor, and the general condition of the patient.
Radiation therapy can be
internal or external. The health care team makes their choice based on the type of cancer being treated.
To start, the radiation
therapist locates and marks the tumor location on the skin of the patient to better target and adapt the
irradiation field. This allows the specialist to accurately
treat the cancer while sparing surrounding healthy tissue. Thanks to advances in medical imaging, targeting is more accurate now. Once every
preparation is in place, the patient will start the treatment; usually 1 session daily, 5 days a week. Each
session is short, lasting a few minutes; and it is absolutely painless. External radiation therapy does not
require hospitalization and can be done as an outpatient procedure.
However, the first session, which
devoted to the identification of the area to be irradiated (known as irradiation field) can take up to 2
hours. It was at this point that the specialist
will calculate doses and "mark" on the skin the important points to ensure everything goes well during the
entire treatment. This marking is done by tattooing. The radiation oncologist will also
determine the position of the patient and the irradiation technique to be used.
The modalities of treatment are
calculated by computer for accuracy.
At each session, a
precise dose of radiation is delivered to the tumor. It is important that the appropriate
dosage is given to the patient in order to damage the DNA of the cancer cells and minimize the side
effects. The sessions will be repeated in a
rigorously established rate; therefore it is important for the patient to undergo the specific number of
sessions recommended by the health care provider to the end of the therapy.
Sometimes, in the case of
small tumors, the radiation source is implanted very close or directly into the tumor. This is called
internal radiation therapy or brachytherapy. This therapeutic procedure requires surgical intervention, but
it allows the specialist to hit the tumor
with higher doses of radiation.
Brachytherapy works by
the introduction of radioactive substances, which are sealed in a thin wire,
catheter, or tube, in order to release radiation to the
tumor. The source is left in a few days (4-5);
although for some cancers, the
implant can be left in place permanently. This requires hospitalization in an
insulated and protected chamber during this period to protect others while the
patient is having the implant.
Brachytherapy is mostly
indicated in the treatment of head and neck cancers,
breast cancer, gynecological
cancers (endometrial cancer, vaginal cancer, cervical cancer) thyroid cancer, prostate cancer, oral cancer.
The radiation treatment
can be aimed at shrinking the tumor in order to make it more easily operable; in this case, the radiation
therapy precedes the surgery. Or it can follow to destroy cancer cells that have escaped the surgery. This
reduces the risks of relapse. Internal radiation therapy can also be
combined with chemotherapy.
Some key points to know
about radiation therapy:
• It involves exposing
the diseased site to the radiation field in order to kill cancer cells (please see cancereffects.com for more info)
• The radiation can be
external (external radiation therapy), or internal (brachytherapy or internal radiation
• Brachytherapy implies
the implantation of the radiation source close or directly into the tumor. It requires a hospital stay of several
days in an isolated room.
• The therapy can be associated with
surgery and/or chemotherapy. Choice of combination depends on the
location of the tumor, its stage and general condition of the patient.
• Radiation therapy tends
to be done as an outpatient procedure; sessions are of short duration, with the exception of the first one
which is devoted to the identification of the area to be irradiated and determination of modalities of the
• Radiotherapy also
causes adverse reactions, but radiation side effects are usually transient, disappearing at the end of the
treatment. They vary depending on the irradiated
area and primarily affect the skin and mucous membranes. Please see radiation side effects for more information.