Photodynamic Therapy (PDT)

In the fight against cancer, science has tried to come up with effective treatments against precancer in order to keep patients from having skin cancer.  Sometimes, though, the precancerous cells can be resistant to specific treatments, such as drugs, or can keep coming back after the growths have been scraped by scalpels or destroyed by lasers or cryotherapy.  That is why photodynamic therapy (PDT) has such promise.

What is Photodynamic Therapy?

Photodynamic therapy essentially combines two methods into destroying precancer cells before they become cancerous.  It combines specific wavelength lights and drugs to destroy the precancerous skin growths.

The patient takes a photosensitizer, which is a kind of drug that makes the precancerous cells vulnerable to light.  This drug can be taken either intravenously or can be topically applied.1  The laser light is then applied at a specific wavelength, which interacts with the photosensitizer to destroy the precancerous cells.2

The potential of PDT has actually been around for over 100 years, but it’s only been the recent advancements in the fields of cancer biology and photobiology and the technological advancements in photonic devices, such as LEDs and lasers, that have enabled doctors to be able to use these treatments as a way to battle precancer and cancer. 1

Benefits of Photodynamic Therapy

There are many advantages to the use of photodynamic therapy when it comes to treating precancerous skin growths such as actinic keratoses.  One such advantage is that photodynamic therapy is considered to have limited levels of toxicity and invasiveness to the patient because it utilizes laser technology and drugs to eliminate the precancerous cells before they can become cancerous.  It also has a track record of being able to successfully eliminate precancerous skin lesions.4

Another of PDT’s advantages is that it can be easily localized to a specific area on the skin.  This is achieved thanks to the photosensitizer and the light.  The doctor can directly control which tissues and cells receive the light and which tissues and cells will absorb the greatest concentration of the photosensitizer.1  This allows for maximum effectiveness of the PDT.

Another added benefit of photodynamic therapy is that there are several ways to administer it, depending on the type of precancer or cancer the patient has.  For skin cancer or precancerous tumors, light-emitting diodes (LEDs) are used to administer the photodynamic therapy.2

As with many new treatments, photodynamic therapy can be used in conjunction with other available therapies, including chemotherapy, cryosurgery, radiation, conventional surgery, and more.2

Disadvantages of Photodynamic Therapy

While photodynamic therapy has many useful features and benefits for its patients, it also has a few drawbacks.  One main drawback is that the light that is used to activate the photosensitizer can only pass through about 1/3 inch (1 cm) of tissue.  As a result, photodynamic therapy is only effective for tumors or lesions on the skin or just under the skin.  Consequently, photodynamic therapy only works well on tumors or lesions that are relatively small in size; the light cannot pass completely through larger, deeper lesions.2

In addition, photodynamic therapy is not a very effective treatment against cancer that has spread to other areas of the body; it is best used for cancer that is localized in one area of the body.2

There is still some question on how long the effects of photodynamic therapy will last.  While it has shown that it can eliminate precancerous cells, the question is how long will this keep precancerous cells from coming back.  This question arises mostly because photodynamic therapy has been used on precancerous cells only recently.  This means that more data needs to be gathered and analyzed before a definitive answer can be concluded.

This, of course, will make insurance companies question whether this is a legitimate treatment or not.  As a result, some insurers may not cover photodynamic therapy as a legitimate treatment option for precancer.

After a patient receives photodynamic therapy, his or her eyes and skin can be sensitive to light for around 6 weeks after treatment.  This is why it is recommended that they avoid direct sunlight for at least 6 weeks after treatment.  All patients are recommended to avoid all contact with sunlight for the first 48 hours after photodynamic therapy; even being in moderate sunlight for a minute or two can cause an immediate reaction where the skin turns a deeper color of red and experiences a burning sensation.5

One other consideration to note of when considering photodynamic therapy as a treatment option is that, while the risk of damage to healthy tissue is low, PDT can cause pain, swelling, burns, and scarring in healthy tissue near where the laser is targeted on the skin.2

Photodynamic Therapy Can Eliminate Precancer Via Photosensitizers and Lasers

Thanks to the advancements in science and in the understanding of how cancer cells work, photodynamic therapy enables doctors to stop precancer from becoming cancerous. This is done via a combination of photosensitizers and lasers to eliminate the precancerous skin lesions, such as actinic keratoses.

Thanks to its non-invasive and effective method, precancer patients have another treatment option to consider in order to prevent their precancerous skin lesions from developing into skin cancer, which will benefit their health and peace of mind.

References

1 Photodynamic Therapy for Cancer – National Cancer Institute (2004, May 12). From National Cancer Institute at the National Institutes of Health: www.cancer.gov/cancertopics/factsheet/Therapy/photodynamic

2 Ibid

Skin cancer: Treatments and drugs – MayoClinic.com. (2010, August 18). From MayoClinic.com: www.mayoclinic.com/health/skin-cancer/DS00190/DSECTION=treatments-and-drugs

4 Photodynamic Therapy (PDT) – Treatment & Information. (2011). From HealthNews.org: www.dermanetwork.org/information/pdt.asp

5 Uses and Side Effects of PDT Drugs. (2011). From American Cancer Society: www.cancer.org/Treatment/TreatmentsandSideEffects/TreatmentTypes/photodynamic-therapy