Photodynamic therapy

Kohala Coast, HI

- Photodynamic therapy (PDT) is a highly effective treatment for actinic keratosis (AK), but it has other molecular targets that result in benefits for improving the appearance of photoaged skin, said C. William Hanke, M.D., M.P.H., at the Winter Clinical Dermatology Conference.

"PDT works. For that reason, I enjoy talking about it and consider it a treatment that every dermatologist should offer," said Dr. Hanke, visiting professor of dermatology, University of Iowa, Iowa City.

In addition to clearing AKs and providing a field effect, 5-aminolevulinic acid (Levulan, DUSA) PDT targets oxyhemoglobin and melanin so that it improves redness and brownness in photodamaged skin. A recently published study investigating the cellular molecular effects after PDT for clinically apparent photodamage on the forearms also reported it may provide some retinoid-like benefits, but with the changes occurring more rapidly than with topical retinoid therapy.

Serial analyses after PDT using 5-ALA and a pulsed dye laser (PDL) showed increases in type I and type III procollagen messenger RNA as well as in types I and III procollagen.

"This is an important study. By describing the molecular basis for its efficacy, it really puts PDT on the map," said Dr. Hanke.

Based on several published articles, PDT also appears to be a useful treatment for actinic cheilitis. Results from one study using 5-ALA with a two- to three- hour incubation period and PDL activation with nonpurpuric fluences and two to three passes showed a 68 percent complete clearance rate after a mean of 1.8 treatments.

"Two or three treatments may be needed for optimal results, but the treatments are easy to tolerate and certainly much better than using the CO2 laser that produced a wound lasting three to four weeks," Dr. Hanke said. DT