May 25, 2000 -- Lasers may be the wave of the future for treating the irritating skin disorder known as psoriasis. Researchers have found that zapping the scaly red patches even just once can get rid of them and is much safer than the standard therapy of sitting in a box of ultraviolet light.
Psoriasis is a red, scaly rash that most commonly occurs on the elbows, knees, scalp, and genitalia, although it can affect many other areas of the body. It is most often first diagnosed in people in their 20s but it can occur in children less than 10 years old. The rash usually comes and goes and can be brought on by several factors including cold weather, stress, skin trauma, and certain drugs. Most cases of psoriasis can be treated with steroid skin creams. However, more severe cases often require exposure to intense ultraviolet rays, called phototherapy.
Although this light therapy is very effective, it exposes patients to damaging ultraviolet rays, much like sitting out in the sun. So researchers have been hunting for a way to treat people with psoriasis without having to damage their skin and increase their chance of getting skin cancer.
Compared with traditional phototherapy, the handheld laser is able to focus the energy directly on the areas of the skin with the rash and spares the surrounding skin from unnecessary radiation exposure, says study co-author Charles R. Taylor, MD. This reduces short-term side effects like burning or itching and long-term effects like wrinkling and cancer, he adds. Taylor is an assistant professor of dermatology at Harvard Medical School in Boston.
Taylor and colleagues evaluated the laser in 13 patients with four or more psoriasis patches. Each patch was given several doses of laser radiation -- anywhere from one to 20 treatments -- during the 10-week treatment period.
High doses of radiation produced significantly better results than medium or low doses. Four months later, areas that were treated with medium or low doses all had recurrences. Areas that were treated with high doses remained in remission, even after a single treatment, although blistering was common. The results are published in the May issue of the journal Archives of Dermatology.
Doctors say laser treatment is unlikely to replace phototherapy in psoriasis management. "Laser treatment appears to be effective for resistant cases", but it's probably not worth the cost for mild or moderate cases, says Harold Brody, MD, clinical professor of dermatology at Emory University School of Medicine in Atlanta.
Like the laser, phototherapy also uses ultraviolet light to clear psoriasis patches. "Dermatologists often have a light box, mounted on the back of a door, that emits different wavelengths of ultraviolet light," Brody tells WebMD. "Patients simply stand in front of it at prescribed intervals, usually after taking an oral drug called psoralen." The drug increases the effects of light on the skin.
But due to the risk of cancer, this approach is only used when symptoms aren't controlled with steroid skin creams. "For moderate to severe cases, several months of phototherapy is often needed to resolve symptoms, even with two treatments a week," adds Brody.
At present, most health plans cover phototherapy and few, if any, cover laser treatment. But its potential to eliminate 25 or more office visits with every outbreak, while reducing the risk of cancer, may cause the managed care industry to take notice of this effective new treatment.
The study was supported in part by Laser Phototonics Inc. of San Diego.
- A recent study showed that a laser beam of ultraviolet light can clear psoriasis patches in a single treatment with a fairly long remission, but blistering was common.
- Unlike traditional phototherapy, laser treatments spare surrounding healthy tissue from unnecessary radiation exposure, reducing the risk of cancer and premature aging.
- Several months of phototherapy is often needed to clear moderate to severe recurrences, but treatments are usually covered by health insurance.