New Approach Prevents Skin Cancer Using Photodynamic Therapy (PDT)
By William Nelson
Every year there are more new cases of skin cancer than breast, prostate, lung and colon cancers combined. One
in 5 Americans will get skin cancer in their lifetime. 90% of skin cancers are caused by excessive sun exposure,
yet fewer than 33 percent of adults, adolescents, and children routinely use sun protection.
Cancer prevention and early detection techniques could eliminate up to 100,000 cancer cases and 60,000 US cancer
deaths each year. New technologies in the evaluation and treatment of sun damaged skin could have a positive impact
on changing these statistics.
The same sunny weather that attracts so many tourists and new residents to the sun-belt also increases the risk
of skin cancer. The effects of chronic sun exposure result in superficial sun spots that are visible and also
invisible changes that occur under the skin’s surface. Ultraviolet photography and photodynamic therapy (PDT) are
two recent developments that should help in the early detection and treatment of both types of pre-cancerous skin
Early Detection with UV Photography Ultraviolet (UV) photography offers a very useful screening tool to help the
skilled physician detect sun damaged skin that may not be visible upon a routine examination. Visual inspection can
only detect changes on the skin’s surface, but damage due to sun exposure occurs beneath the outer layer of
The UV camera briefly shines ultraviolet light on the face. UV light is able to penetrate 1.5-2.0 millimeters
under the visible dead layer of skin and focus on the actual living portion where sun damage originates. The
advantage to the doctor and the patient is that this technology allows for much earlier detection of skin problems
before they develop into pre-cancers that are visible on the skins surface. After finishing the treatment plan, the
doctor should take another UV photo to verify the treatment efficacy. UV photography also helps evaluate other skin
conditions including acne, oil balance, hydration, inflammation, growths, fungi, pH, and thin skin due to reduced
collagen which makes it an ideal tool to evaluate all problem skin.
After the damage to the deeper layers of skin, superficial signs of sun damage may eventually appear on the
surface. The most common surface lesion is known as actinic keratoses (AK). AKs usually appear as rough or scaly
patches. They may also flake, crust, and may temporarily disappear and then return.
An AK is most likely to appear on the face, ears, scalp, neck, backs of the hands and forearms, shoulders, and
lips - the parts of the body most often exposed to sunshine. The scaly patch may be light or dark, tan, pink, red,
or a combination of these…or the same color as your skin.
It is estimated that 10-20% of untreated AKs will develop into squamous cell cancers. If treated early, almost
all AKs can be eliminated without becoming skin cancers. If you have AKs, it indicates that you have sustained sun
damage and have a higher risk for developing all types of skin cancer - not just squamous cell carcinoma.
The more keratoses a person has, the greater the chance that one or more may turn into skin cancer. People may
also have up to 10 times as many subclinical (invisible) lesions as visible, surface lesions. These invisible
lesions were undetectable until the development of the UV camera.
Treatment options The most common treatment options for AKs have traditionally involved topical ointment 5-FU
(Effudex), laser resurfacing, or chemical peels. To avoid the prolonged recovery period and possible scarring
associated with these techniques, photodynamic therapy has been developed.
Photodynamic therapy (PDT) is the treatment of choice for the invisible deeper sun damage as well as the visible
pre-cancerous AK lesions. PDT involves a two step process that has been proven effective in clinical testing. This
treatment cleared 100% of the AKs in 2/3 of the patients after one treatment.
The first step is the application of a topical solution called Levulan. Abnormal cells have a much greater
affinity for the solution and absorb it while the healthy cells do not. The solution is left on for an incubation
period lasting anywhere from 15 minutes to 18 hours.
The second step of PDT is to apply a concentrated light source to activate the chemical reaction which destroys
the abnormal cells. Since the solution is absorbed only in the damaged cells, the healthy cells are not affected.
This process can cause a mild burning sensation during the treatment. Usually, this improves immediately after
treatment and ends within 24 hours.
Following the treatment, most patients experience mild swelling, redness, and a peeling of the AK lesions and
the surrounding tissue. Patients choosing a more aggressive treatment will experience more peeling and/or crusting
of the damaged skin that resolves within in one or two weeks. The doctor can easily control the severity of these
reactions by limiting the incubation period and the amount of exposure to the light source.
Patients not willing to experience a prolonged recovery time after the procedure may choose a more mild
treatment and return to work after a day or two. The tradeoff is that they will require more treatments to achieve
the same clinical results.
In addition to eliminating AKs and the subsurface skin damage, PDT has also been effective in improving the
appearance of the skin by greatly reducing moderate to severe acne (including cystic acne), reducing color
splotches, lessening the fine lines, and decreasing pore size.
Anyone who currently has, has had, or wants to prevent AKs or pre-cancerous skin lesions should be evaluated and
treated using UV photography and photodynamic therapy (PDT).” Once a person has been successfully treated using
this approach, it is recommended they return for a yearly follow up to prevent future problems.
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