Questions and Answers

How does Photodynamic therapy (PDT) work?

Photodynamic therapy is an old science with newly emerging applications in dermatology. In the early part of this century it was noted that while neither acridine orange nor light was toxic to paramecia, the two together resulted in rapid cell death. This observation led to the realization that exposure of tissues to certain photosensitizing chemicals with subsequent exposure to light could cause tissue damage. Because skin is so easily accessible to light based therapy, there has been a great deal of interest recently in photodynamic therapy. We have found that a chemical, aminolevulanic acid, can penetrate the top layer of cells and selectively find sundamaged cells, certain skin cancers, and pilosebaceous units. As it enters those cells, it is converted to protoporphyrin, which can be easily affected by exposure to light. Light energy applied to the protoporphyrin generates singlet oxygen or oxygen radicals, which results in the death of the targeted cells.

This concept has found wide application in dermatology. We can use photodynamic therapy to treat actinic keratoses, superficial skin cancers, acne, thick oily sebaceous skin, and sebaceous hyperplasia. There is also some interest in using photodynamic therapy for rejuvenation of sundamaged skin. While the various protocols for treating each of these conditions are still being refined, we have had a great deal of experience at the Center for Laser Surgery in using photodynamic therapy and can generally tailor a treatment to meet an individual's specific needs. Please ask us about this very exciting new form of therapy.

Photodynamic Treatment for Skin Cancer

What types of conditions can be treated with PDT?

Photodynamic therapy has been effective in the treatment of actinic keratoses (pre-cancerous spots), some types of skin cancer, sundamaged skin, acne, warts, and other diseases.

Is PDT uncomfortable?

During PDT the skin is washed several times and the activated substance is applied. Either of these may cause stinging. During therapy, burning may occur and local anesthesia may be used to prevent this. Following treatment, there may be some transient itching and burning.

Photosensitivity

After PDT, a small amount of activated substance remains in the skin for 24 to 48 hours. Sunlight and even indoor light may affect this and cause redness and itching. Use of sunscreen and a hat may diminish the undesired effects.

Itching/Burning

Most people experience mild burning and itching for about one hour after the procedure, although this can last a day or two. Mild to moderate redness may be experienced for 24 to 48 hours. Routinely, gentle emollients should be applied to the skin. More focused prescriptions may be suggested by your doctor.

Swelling

Areas most likely to swell are around the eyes. This will subside within several hours. Application of ice or cold packs may help.

Peeling

Peeling of treated skin may occur several days after the procedure and can be alleviated by gentle washing and application of a slightly thicker moisturizer.

Please call for an appointment to meet with our expert, Dr. Susan Elliott.