Michel McDonald, M.D.
Treatment shines light on skin lesions
When most people hear about skin cancer, they typically think about it being caused by sun exposure. A new treatment option being used at Vanderbilt to remove pre-cancerous skin problems, however, actually uses a form of focused light therapy.
Photodynamic therapy may sound and look like laser therapy, but it's not. It uses a wavelength in the light spectrum that has been shown to be beneficial against actinic keratoses, a pre-cancerous skin problem, when combined with a special type of acid that can be applied to the skin.
“The substance is called Levulanand it isaminolevulinic acid,” said Michel McDonald, M.D., assistant professor of Medicine.
The acid is applied to the skin and allowed to absorb for at least one hour before the light therapy begins. “When the light is applied to the skin the substance soaks the light in and then destroys the cells or the keratosis,” said McDonald.
McDonald said photodynamic therapy is a good alternative for patients who can't tolerate other treatments, like a topical cream for pre-cancerous areas, and for those who have large areas of concern.
“This is something I would recommend if they have multiple spots on their scalp or multiple little pre-cancerous lesions on their face.”
McDonald said patients with just one area needing attention are better suited with a treatment that can be performed faster, like freezing.
Photodynamic therapy does have a few drawbacks. Once exposed to the intense light therapy, patients can't go out in the sun for about two days without being completely covered up.
“You are sensitive to light, so you need to wear sun protection. Sunscreens don't work because they block out ultraviolet light, so when you have this done you must be prepared,” cautioned McDonald.
McDonald said the light is typically applied for a little more than 15 minutes, but can be stopped sooner if the patient is uncomfortable, and repeated on another visit.
It takes about four weeks before results can be seen, and additional treatments may be needed. Also, photodynamic therapy is not a permanent fix for pre-cancerous lesions, McDonald said.
“Sun damage that is present in that area is still there in your DNA, so eventually over a couple of years you are going to have more in that field that was treated. It's just going to prevent perhaps some keratoses from going on to squamous cell carcinoma.
“So, that is why it is a good idea to have been treated,” said McDonald.
McDonald said that prevention is the number one goal, but she hopes to be able to treat most skin cancers in the coming decade without having to perform surgery.
The Food and Drug Administration has approved photodynamic therapy for actinic keratoses, but McDonald said it is also being used more frequently to treat acne.