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Treating
esophageal cancer with PDT |
Light
- so common that we usually take it for granted, but so basic that we couldn’t
live without it.
Ancient
civilizations practiced different forms of phototherapy (treatment with light).
Hippocrates recommended the use of sunbaths in ancient Greece, while in the 20th century
Switzerland, Bernhard and Rollier called it heliotherapy and used it in the treatment of
tuberculosis.
It
is absolutely required by the body in the production of vitamin D and we know
that a lack of sunlight, particularly in winter, leads to depression in a
syndrome called SAD (Seasonal Affect Disorder).
Today,
we use many types and forms of light in treating illness and disease, including
ultraviolet, infrared and the highly concentrated light of a laser.
PhotoDynamic
Therapy
Given
the long history of treating with light, it should come as no surprise that an
effective method of battling cancer with light has been discovered. Cancer, the
second largest disease killer of mankind, can affect almost every part of the
human body. For this reason, many different kinds of treatment have been
developed, including surgery, radiation, chemotherapy and hormone therapy.
PhotoDynamic
therapy, or PDT, offers a unique solution to those suffering from cancer mainly
because it does not require hospitalization, surgery, chemotherapy, radiation or
immunotherapy. It can be used routinely and repeatedly as it selectively
destroys only affected cancerous cells, thus proving it to be one of the most
effective, and safest, forms of treatment.
But,
what is PDT? Well, in 1900, a medical student named Oscar Raab worked in a
pharmaceutical laboratory observing the effect of minute concentrations of
acridine, a hydrocarbon dye, on single-celled animals called paramecia. He
noticed that somehow daylight was affecting the results, and upon more careful
study, discovered that the acridine killed the paramecia only in the presence of
light, while acridine alone and light in the absence of the acridine, did not.
Light served to activate the dye, which became known as a photosensitizing
agent. In fact, in 1903, a Nobel Prize was awarded to Niels Finsen for his
pioneering research in light treatment.
Over
the years, other photosensitizing agents were discovered and systematic clinical
studies were undertaken, especially in the 1970s, led by Dr. T. J. Dougherty of
the Park Institute in Buffalo, NY, in the United States. He used porphyrin compounds as the photosensitizing agents. This research
ultimately led to the U.S. Federal Drug Administration (FDA) to approve it as a
cancer treatment.
The
technique itself is rather straightforward. The photosensitizing agent is either
injected into the patient’s bloodstream or applied topically. It concentrates
in cancer cells of all types. Then, the mass, with its accumulated
photosensitizing agent, is subjected to a dose of light of a specific
wavelength. The light activates the photosensitive agent causing the release of
a highly reactive free-radical oxygen molecule that leads to the destruction of
the cancer cell (necrosis) and especially the blood vessels feeding it. Often, the necrotized tissue just sloughs away and there is normal healing of
the wound. However, function and structure of delicate non-cancerous underlying
tissue is preserved.
PDT
can be used to treat not only superficial tumors, but, by repeated use, large
tumors in a process called debulking, where the tumor is progressively reduced
in size.
PDT
is not contra-indicated if other therapies are concurrently utilized, i.e.
chemotherapy, while potentially disfiguring results, as can occur with surgery,
are minimized if not entirely eliminated.
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PDT
selectively destroys cancerous cells |
Traditionally,
the limitations have been the photosensitizing agents, as they can have a
“spill-over” effect, thus affecting normal tissue to some degree. Also,
there were inherent limitations of the light sources, usually lasers, in terms
of the depth of penetration through the skin. That necessitated surgery,
particularly endoscopic surgery, in order to be able to introduce the light
source to the location of the tumor. New laser light delivery systems are
currently being developed to address this limitation.
The
Side Effects
So
what are the side effects of PDT? The major side effect is
photosensitivity, or sensitivity to light. While inconvenient, it is
hardly an “unacceptable” risk. While previous types of
photosensitizing agents remained in the body sometimes for several months,
requiring the patient to stay indoors during the day (to avoid getting a severe
sunburn), new agents, like hemoporfin, Foscan, or 5-ALA (a naturally occurring
amino acid) are usually eliminated from the body after 24 hours.
Pain
is the other potential side effect of PDT. A secondary complication, it
results from the breaking down of the tumor tissue, which can cause inflammation
and subsequent pain. But, it can be thought of as a “good pain”, as it
indicates that the process is working! Fortunately, it is usually mild to
moderate and easily controlled with short-acting painkillers.
Other
short-term side effects may include nausea/ vomiting, fever (also associated
with inflammation) and occasionally, a metallic taste. Rarely do any of these
side effects last more than a day or so.
The
Leeds Centre for Photobiology and Photodynamic Therapy in England continues to
do substantial research in this field, and is not limited to just PDT and
oncology. An outpatient clinic specializing in photodynamic therapy has also
recently opened in Ireland, where it is known as Cytoluminescent Therapy (CLT). The clinic employs the
newest photosensitizing agents, derived from green plants, which tend to be more
tumor-sensitive and therefore more effective. Under the leadership of William
Porter, MD, they report astounding treatment results and cannot keep up with
patient demand.
And
Then He Saw Light
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Age-related
macular degeneration is the leading cause of blindness in developing countries |
PDT
is also being studied in non-oncology related illness, including the treatment
of atherosclerosis and both rheumatoid and inflammatory arthritis, among other
diseases.
But
one of the most promising uses is in the treatment of Age-Related Macular
Degeneration (AMD or ARMD). Results are nothing short of exceptional!
ARMD
affects 40% of individuals 75 years or older and is the leading cause of
blindness in developed countries. One form of ARMD, the “wet” form, is the
result of new blood vessels formation. Termed “choroidal neovascularisation”
(CNV), these vessels grow under the center of the retina, in an area known as
the macula. There, these vessels can leak fluid and bleed, causing scar tissue
to form. That scarring can destroy vision in as little as three months!
In
ARMD, the photosensitizing agent is also injected into the patient’s
bloodstream. The light sensitive dye sticks to the inner lining of the new
vessels. Then, the macula of the patient’s eye is subjected to the dose of
light, which activates the photosensitive agent resulting in damage to the blood
vessels, causing them to close, preventing the leaking vessels from doing
further damage.
The
procedure is done on an outpatient basis and takes about 30 minutes.
A
study for the treatment of Age-Related Macular Degeneration with Photodynamic
Therapy was performed in 22 centers in Europe and the United States. Vision was
stable or improved in 61% of patients treated with photodynamic therapy with
virtually no side effects!
As
research continues, the application of light as a treatment modality will expand
and provide a safe and effective means of treating a large variety of diseases.
Amazing,
this thing we call light!
Lev
G. Fedyniak, MD, began his medical career in alternative medicine,
studying acupuncture, herbs and other healing traditions in China,
Hong Kong, Canada, Ukraine and other parts of the world. Recognizing that the
allopathic tradition was a necessary component in treating illness, he trained
in allopathic medicine to obtain the Doctor of Medicine (MD) degree.
Dr.
Lev makes his home in Ukraine
and continues to study new approaches to treating illness and optimizing health
from traditions all over the world. He publishes articles and books in the hopes
of bringing such information to all who need it.
He
can be reached at DrLev@IntegrativeMedicineOnline.com
