Photodynamic Therapy for Cancer
therapy combines a special drug, known as a photosensitizing agent, and a certain light to kill cancer cells.
Some of the drugs are applied topically such as aminolevulinic acid (ALA) and methyl ester of ALA. However, the
most commonly used is injected into the blood vessels. It is called porfimer sodium and this type of treatment
will be the focus of this article. It is non-toxic and absorbed by both healthy cells and cancerous cells.
However, when exposed to a certain light the drug activates, killing the cancer. Photodynamic therapy (PDT) is
sometimes named phototherapy, photoradiation therapy, and photochemotherapy.
Photodynamic Therapy: It’s advisable to get your body used to the light sensitivity it will be
experiencing later. Cover the windows and turn off the lights in your home before your Photodynamic therapy
appointment. Before you leave, it is important to wear socks, long pants and a long sleeved top to your
appointment. Your clothes should be of a tight knit fabric and light in color. Also, bring along gloves, sunglasses
and a hat with a wide brim that goes all the way around.
The time it
takes for the drug to absorb into the cancer cells is known as the drug-to-light interval and can take hours to days. Over time the body cleanses
itself from the drug.
To activate the drug, a
laser is sent through a thin fiber optic strand made of glass and is directed to the cancerous cells. The light
makes oxygen and the drug react together to create a chemical that kills cancer cells. How the strand reaches
the affected area depends on the type of cancer. For example, the strand is placed in the throat with an
endoscope when treating esophageal cancer. With lung cancer, it is put into a bronchoscope so it can be fed into
the lungs. The whole procedure is fairly quick and typically outpatient.
A low powered laser means
that pain is minimal or even nonexistent with Photodynamic therapy. The light is applied anywhere between 5 to
40 minutes, depending on how big the tumor is. In less than a week, dead tissue can be taken out.
Types of or Techniques
Used: There are many ways in which
Photodynamic therapy is used. Besides targeting cancer directly, it can cut off the cancer’s food source by
destroying the blood vessels which feed it. PTD can even turn the body’s own immune system to fight against the
The procedure is
typically painless and can even be repeated in the same area for multiple treatments. After healing there is
little or no scarring. However, you may feel sensitive to light up to 30 days after the procedure. Be careful
about how much time you spend outside. Also, watch your exposure to reading lamps and doctor’s examination
lamps. High heat can also activate the photosensitizing agents still in your body, so be careful with hair
dryers, and other heat sources.
Risks and Side Effects of
Photodynamic Therapy: Though there are no long-term side effects, Swelling is a common complaint of
Photodynamic therapy. It can cause problems with breathing and swallowing and may be painful. Light sensitivity of
the eyes and skin is also common due to the photosensitizing agents used.
While your body is cleansing
itself of the drugs, you may find that your eyes and skin are very sensitive to light. Just a few minutes in the
sun can cause burning and blistering. Your eyes may not only be more sensitive to sunlight but also other forms
of light as well.
Avoiding the sun is a must
but some indoor light exposure is necessary. This helps break down the drug in your skin. After about 30 days,
if you’re concerned, a doctor can test your skin to see if you still have photosensitivity from PDT.
General side effects can
vary from person to person. For example, esophageal cancer treatment may cause stomach upset, vomiting, elevated
temperature, or mild to severe dehydration. With lung cancer PDT treatments you may experience bloody phlegm,
pneumonia, or problems breathing.
experience is unique so ask your doctor what to expect with your Photodynamic therapy procedure.