New Approach Prevents Skin Cancer Using Photodynamic Therapy (PDT)
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 lesions.
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
Visual inspection can only detect changes on the skin’s surface, but damage due to
sun exposure occurs beneath the outer layer of skin,
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
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
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.
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
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.