HARVARD GAZETTE ARCHIVES
Laser lights up treatment of skin disease
By William J. Cromie
Nancy Stuart hated her body. Scaly, red plaques of psoriasis disfigured her arms, legs, trunk, and scalp. Summer was the worst time. She had to cover her entire body. Otherwise people looked at her in disgust or pity. No one would sit next to her on a bus.
Seven months ago, Nancy (not her real name) volunteered for an experiment at Massachusetts General Hospital where researchers at Harvard Medical School are testing a new type laser for treating psoriasis and other skin diseases.
Along with 12 other patients, she had portions of her psoriasis patches irradiated with an intense beam of ultraviolet laser light. Other parts of the plaques were left untreated for comparison. After only five treatments, the redness, scales, and discomfort disappeared on the irradiated areas. Other patients required only a single treatment, lasting a few minutes, to clear their skin. In all cases, the treated areas have remained clear for more than six months.
Standard therapy, in which people are enclosed in a box walled on all sides with ultraviolet lamps, requires 30 or more treatments. And many patients never get rid of especially stubborn patches on their elbows, knees, and lower back.
"Im extremely excited about the treatment results so far, because were able to flatten thick plaques of psoriasis in an unprecedented short time," says Charles Taylor, assistant professor of dermatology. "You can also take previously untreatable plaques and get them to vanish in four to five treatments. The radiation is selective. If plaques cover 20 percent of a persons body, we only irradiate 20 percent, not 100 percent, as in the case of light boxes. That may reduce the risks of skin cancer and accelerated skin aging due to unnecessary exposure to ultraviolet light."
Taylor feels sure ultraviolet lasers will be adapted to treat other common skin maladies that distress millions of people in the United States. These include eczema, chronic itching, sun poisoning, vitiligo, and purple, lichen-looking markings known as lichen planus. Vitiligo produces a loss of pigment, resulting in splotches of light skin on dark-skinned individuals.
"We successfully treated two people with ulcerated lichen planus markings in their mouths," Taylor notes. "Theyre now eating well, something that was difficult and painful for them to do before."
Reducing Cancer Risk
Taylor and his team have treated 39 more patients since they reported their initial success in last months Archives of Dermatology, a journal of the American Medical Association. This new group remains mostly psoriasis-free after two months of follow-up.
Larger numbers of people are now being enrolled in second-phase trials at several centers across the country. These trials will be done to determine the best doses of light to use.
"In the first 13 patients, we discovered that a high enough dose can clear skin in one treatment," Taylor explains. "But such high doses produce a painful blistering that takes about two weeks to heal. Thats impractical to do over a large body area. While the risks of blistering on plaques are unknown, blistering on normal skin is associated with an increased risk of melanoma," a deadly skin cancer.
The researchers believe that such risks can be minimized by lowering the dose significantly. That may increase the number of treatments but only to four to five, still low compared to the 30 or more sessions required with a light box. Also, the box irradiates normal as well as diseased skin, increasing the risk of non-melanoma skin cancer.
In addition, the laser cleared the toughest types of plaques, those on the elbows, knees, and lower back, in four to five treatments. "These often persist even after 30 treatments with a light box," Taylor points out.
The higher doses needed to eliminate stubborn elbow and knee plaques feel like a sunburn for a few days, but patients tolerate it well, according to the researchers.
"As someone once said, even light has its dark side; chronic exposure to ultraviolet light does raise the risk of skin cancer," Taylor notes. "For those blemished with psoriasis, its a quality-of-life issue. Some people would rather have physical and emotional relief now at the expense of an increased risk of non-melanoma cancer in the future." When detected early, such cancers often can be successfully treated.
At present, then, the best use of the laser technique is for localized patches of psoriasis. Patients treated to date have had at least four to five handsized areas removed without problems. The researchers are convinced that the technique will work well with patients who have as much as 30 percent of their bodies covered by the scaly, inflamed-looking deposits. The only areas of the body not yet treated in these trials are the face and groin.
"We treat a palmsized plaque in about one minute," Taylor says.
In the planning stage is a laser that will scan the whole body, adjusting the dose as it goes from areas of normal skin to those of plaque.
"The technology is available," Taylor notes, "but many details remain to be worked out." These include such things as the location and thickness of plaques, the amount of body hair, changes in body curvature, and the patients skin type." He speculates that ultraviolet lasers that can be programmed with such information "may be two years down the road."
Also available soon, Taylor believes, will be lasers to treat eczema, chronic itching, sun poisoning, and other punishing skin conditions. "The future looks very promising for these new types of treatments," he says.
Those with localized psoriasis who are not receiving other treatments and are interested in participating in clinical trials of the ultraviolet laser going on at Massachusetts General Hospital in Boston should call Joanne at (617) 726-1590.
Copyright 2000 President and Fellows of Harvard College