New guidelines from American Academy of Dermatology for treatment of psoriasis with ultraviolet light therapy

Oct 23 2009

Long-standing therapy remains an essential treatment option for select patients

Based on an extensive review of the highest quality scientific literature on psoriasis and the opinion of recognized psoriasis experts, the American Academy of Dermatology (Academy) has released new guidelines of care for the management and treatment of psoriasis with ultraviolet (UV) light therapy, also known as phototherapy. Recommendations for the use of the most common forms of UV light therapy, as stand-alone treatments or in conjunction with other therapies, were outlined, including patient considerations.

Published online in the Journal of the American Academy of Dermatology, this is the Academy's fifth of six sections of the guidelines of care for psoriasis, with four previously published sections focusing on general recommendations for the treatment of psoriasis and psoriatic arthritis, as well as the use of biologics, topical and systemic therapies.

"Although treatment options for psoriasis have expanded considerably in recent years, UV light therapy remains an important treatment option for many psoriasis patients," said dermatologist David M. Pariser, MD, FAAD, president of the Academy. "Over the years, phototherapy has been shown to effectively clear psoriasis, and it is a cost-effective therapy that generally does not suppress the body's immune response like traditional and biologic systemic therapies. However, because this therapy delivers UV light to the skin (a known carcinogen), patients need to be closely monitored by their dermatologists for the potential risk of skin cancer."

Psoriasis is a chronic skin condition which usually develops before age 35 and is characterized by thick, red, scaly patches that itch and bleed. Nearly 7 million Americans are living with this skin condition. Both genetic and environmental factors contribute to causing the disease. Research has determined that psoriasis is linked to multiple genes, but it is not completely understood how it is inherited. However, there are at least nine locations on different chromosomes that are associated with psoriasis, but researchers have not identified the specific genes that are linked to the genetic transmission of the disease.

Types of UVB Therapy

One type of phototherapy that has been used successfully to treat psoriasis for more than 75 years is broadband (BB)-UVB therapy. As its name implies, BB-UVB is used to treat a large area of psoriasis by exposing the affected skin to a specific wavelength of UVB light.

A newer form of UVB therapy introduced in the United States in the 1990s that is commonly used to treat psoriasis is narrowband (NB)-UVB therapy. With this therapy, narrower bands of UVB wavelengths are administered to the affected skin, and studies have shown NB-UVB therapy to be more effective in clearing psoriasis than BB-UVB.

"Studies have shown that psoriasis patients treated with NB-UVB therapy had better results than those treated with BB-UVB, including more rapid clearing and better remission rates," said Dr. Pariser. "While both therapies are generally well-tolerated, patients must be educated as to the potential long-term side effects of UVB - including an increased risk of skin cancer and premature aging - and protect their eyes by using goggles to decrease the risk of UVB-related cataracts that could form from prolonged exposure."

Other minor side effects of BB-UVB therapy include redness, itching, burning and stinging. Burning also is a possible side effect of NB-UVB, and Dr. Pariser noted that, although not commonly reported, there have been instances of skin blistering after exposure to NB-UVB. In addition, neither BB-UVB nor NB-UVB therapy are known to cause birth defects or disrupt a pregnancy and can be prescribed to women during pregnancy or while attempting to conceive.

While studies examining the use of and long-term safety of UVB therapy in children are limited, Dr. Pariser explained that this therapy could be considered as a second option in selected children whose psoriasis does not respond to topical therapy as long as the light therapy is closely monitored by a dermatologist.

In some cases, UVB therapy is effective when used by itself to clear psoriasis, but dermatologists commonly use this therapy in combination with topical or systemic medications. Dr. Pariser emphasized that the decision to use combination therapy should be made on a case-by-case basis and tailored to meet individual patients' needs.

PUVA Photochemotherapy

"PUVA" is a term applied to a group of therapeutic techniques that use psoralens - a group of photosensitizing compounds - to sensitize cells to the effects of UVA light. Psoralens are available as oral or topical medications that patients must use before being exposed to UVA light, or in a bath formula that patients soak in prior to UVA exposure (this form of PUVA is not as widely used). Two large, multicenter studies have demonstrated the efficacy of PUVA in the treatment of psoriasis, and Dr. Pariser noted that PUVA treatment often leads to the clearing of psoriasis typically within 24 treatments with remissions lasting between three and six months.

"The introduction of PUVA for the treatment of psoriasis was a major advance for patients with severe psoriasis, as it offered them an outpatient therapy rather than other treatments that required hospitalization," said Dr. Pariser. "However, studies show that high cumulative exposure to oral PUVA is associated with an increase in the risk of non-melanoma skin cancer, particularly squamous cell carcinoma, which is why dermatologists often reserve PUVA for psoriasis patients who have not responded favorably to other treatments."

In an effort to minimize the total dosage of PUVA, dermatologists often combine PUVA treatments with other therapies (such as retinoids) or in rotation with other treatments. In addition to the increased risk of skin cancer and skin aging with long-term use, other common side effects of PUVA include redness, itching, dryness, irregular pigmentation, nausea and vomiting. PUVA also is not recommended for use in children or in patients with certain medical conditions, which is why dermatologists closely evaluate patients before PUVA is considered as a treatment option for psoriasis.

Targeted Phototherapy (Excimer Laser)

With the introduction of the 308 nm monochromatic xenon-chloride laser for psoriasis in 1997, the use of phototherapy to treat localized lesions became more practical and more widely available. Excimer lasers selectively target affected lesions without treating unaffected skin - therefore minimizing the potential risk of exposing uninvolved skin to UV radiation. Another advantage is that since only the affected areas are treated, higher doses can be administered in fewer treatment sessions.

Although numerous studies have demonstrated that treatment with the excimer laser can clear psoriasis, there is limited information on the duration of remission and the recommended dosage and scheduling of therapy. Dr. Pariser explained that most patients experience long-term improvement following treatment with the excimer laser, and currently the dose of energy delivered is guided by the patients' skin type and thickness of the psoriasis plaques.

"Typically, patients receive treatment with the excimer laser two to three times a week, with a minimum of 48 hours between treatments," said Dr. Pariser. "Side effects are minimal and are limited to the treatment area, with redness, burning and darkening of the skin being the most common. There have been cases where blistering has occurred with the use of higher doses of energy, but for the most part treatments are well-tolerated - even in children."

Patient Considerations for UV Light Therapy

Like all treatments for psoriasis, some patients make better candidates for UV light therapy than others. Dr. Pariser added that before UV light therapy is considered, all patients must have a complete history and physical examination and be made aware of the potential long-term risks of this treatment.

"Patients with a known history of lupus (a chronic inflammatory disease) or xeroderma pigmentosum (a genetic disease characterized by extraordinary sensitivity to sunlight) should not be treated with phototherapy," said Dr. Pariser. "In addition, patients with atypical nevi, multiple non-melanoma skin cancers, multiple risk factors for melanoma, a history of melanoma, a history of photosensitivity disorder, or who are taking photosensitizing medications or are immunosuppressed as a result of organ transplantation should be screened carefully before starting UV light therapy."

Recommended dosing guidelines for both BB-UVB and NB-UVB vary by skin type, with light-skinned patients receiving much smaller initial and incremental doses of UV light than darker-skinned patients.

"For the right patients and with close monitoring by a dermatologist, UV light therapy can be a safe and effective treatment for psoriasis patients who might not have responded well to other traditional therapies or for various reasons might not be good candidates for systemic medications," said Dr. Pariser. "Dermatologists can recommend the best treatment plan for patients with mild to severe psoriasis, helping them improve their condition and overall quality of life."

SOURCE American Academy of Dermatology