PDT effective in medical and cosmetic uses

Photodynamic therapy (PDT) is emerging as a useful tool in medical and cosmetic dermatology. The target is the same for skin damaged by the sun and other environmental insults. These actinic keratoses (AK) are precursors to skin cancer that degrade the texture and appearance of the skin.

Nellie Konnikov, MD, clinical professor of dermatology at Harvard Medical School and chief of dermatology at Veterans Administration Boston Healthcare discussed the role of PDT in treating aging skin March 5 during “Photodynamic Therapy in Medical and Aesthetic Dermatology” (U071), which evaluated both medical and cosmetic uses. The Food and Drug Administration has approved PDT for treating AKs, she said. The procedure removes 90-100 percent of AKs to produce clear medical benefits, and it rejuvenates treated skin to produce clear cosmetic improvement.

Maria M. Tsoukas, MD, PhD, discusses the use of phototherapy for the treatment of actinic keratoses.

That combination of effects makes PDT useful for field treatment of AKs and for cancer prevention in high-risk patients, such as solid organ transplant recipients, said Maria M. Tsoukas, MD, PhD, associate professor of dermatology at the University of Illinois College of Medicine in Chicago. It can also be useful for acne, skin rejuvenation, and cosmesis, she said.

PDT is a combination of a photosensitizing drug, most commonly aminolevulinic acid, and exposure to light energy. Light energy on sensitized skin produces free oxygen radicals to target dysplastic proliferating cells and malignant epidermally derived and immune cells while sparing mesenchymal tissue, including the dermis. Because the sensitizer is applied to broad areas, such as the exposed skin of the entire face and scalp, PDT can treat the entire field rather than targeting individual lesions.

A variety of light sources can be used, including lasers, filtered xenon arcs, metal halide or fluorescent lamps, LEDs, intense pulsed light, and natural sunlight. Blue light is most effective for surface lesions, while red light penetrates more deeply into the dermis and is more effective for deeper treatments.

Narrow spectrum emissions provide shorter treatment times than broad spectrum illumination, Dr. Tsoukas said. Sunlight can also be an effective light source for PDT, which may be more convenient for some patients.

European studies have shown sunlight AK eradication to be similar to artificial illumination, she said, with similar results reported in U.S. studies. Sunlight PDT can be cost-effective, allows the patient to spend less time in clinic, and generally produces less pain.

Pain management can be an issue regardless of the light source used. A portable fan and ice packs may help cool the face during and after treatment. Acetaminophen provides sufficient pain relief for many patients, although some may require topical lidocaine.

PDT can be used on all skin types and is particularly helpful in solid organ transplant patients, who have elevated rates of skin cancer. Immunosuppressed patients need dermatologic exams every two to six months, depending on the degree of cutaneous carcinogenesis. PDT is a convenient and cost-effective method to treat field cancerization.

Repeated split-face trials have shown PDT to be as effective as imiquimod for AK therapy. PDT treatment is faster than imiquimod, eliminates concerns about patient compliance, and produces a slightly better cosmetic outcome, Dr. Tsoukas said. In immunosuppressed patients, PDT showed clinically better results than topical imiquimod. Another alternative is pretreatment with topical 5-fluorouracil for two weeks followed by PDT.

“Aging is a privilege,” Dr. Konnikov said, “but that doesn’t mean we can’t fight it every step of the way. PDT can help that battle.”

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