Sunday, February, 12, 2012

Psoriasis - Phototherapy

Table of Contents

Treatments may be repeated two or three times a week. They should never be performed more frequently than once every other day, because the full effects of the treatments are not evident for 48 hours.It takes an average of about 25 PUVA treatments for the full effect to be seen, but during that period, treatment intensity may vary.

  • If there is no response after 10 treatments, the doctor may increase the UVA energy.
  • If there is still no response after 15 treatments, the psoralen dosage may be increased.
  • If a patient's skin does not improve at all or worsens, the treatment is temporarily stopped. PUVA may be causing a toxic response in such cases, and often, the condition gradually improves over the following 2 weeks.
  • If the skin does not improve over the following 2 weeks, PUVA treatment has failed. If skin improves during this resting period, treatment resumes.

Maintenance Phase. Once the psoriasis has improved by about 95%, the patient may be put on a maintenance schedule. Often only one or two treatments a month are needed, but some people may need more frequent treatments. As maintenance continues and the interval between treatments lengthens, patients may become more susceptible to tanning and sunburn. They should reduce exposure to natural sunlight during this time.

Success Rates. Nearly 90% of patients achieve marked improvement or clearing within 20 - 30 treatment sessions.

Combinations. Combining acitretin, calcipotriene, methotrexate, or tazarotene gel with PUVA may enhance its effectiveness or increase the response. In addition, combinations may allow for lower doses of radiation or medications to be used, minimizing side effects. Retinoids may also help protect against skin cancers (methotrexate may increase the risk). In some cases, patients who are resistant to PUVA or PUVB may respond when the phototherapies are combined.

Side Effects and Complications of PUVA.

  • The psoralen methoxsalen causes a general ill feeling and nausea in 20% of patients. Dividing up the dose and taking it in 15-minute intervals with food, or taking ginger 20 minutes before taking the drug may be helpful.
  • Skin reactions, including itching, sunburn, and blistering, are common. These can generally be avoided with careful administration of PUVA therapy and protective measures. Antihistamines, baths with special oatmeal preparations (Aveeno), and capsaicin ointment (Zostrix) may help.
  • After treatment, white spots commonly develop in the areas where psoriasis plaques were, particularly in people with naturally darker skin. If these spots are troublesome, tanning products may help darken them. Small, dark raised spots called PUVA lentigines may also develop in affected areas with long-term treatment.
  • Prolonged standing may trigger fainting in people with certain heart or blood pressure problems.
  • People with liver disease should discuss using topical psoralens, because oral forms may have adverse effects on the liver.
  • UVA penetrates the skin more deeply than UVB, so there is a greater danger of deep skin damage, accelerated skin aging, and skin cancers. Anyone who needs to avoid sunlight should not get this treatment.
  • The procedure increases the risk for cataracts if the eyes are not protected for up to 24 hours after treatment.

Special Warning on PUVA and Skin Cancers. It has been known for some time that PUVA can change DNA and cause genetic mutations. PUVA is known to increase the risk for squamous cell skin cancer and slightly increase the risk for basal cell skin cancer, both of which are nearly always curable. One study also reported an increased risk of melanoma. The risk for skin cancers is higher in people who have:

  • A family or personal history of skin cancer
  • Light skin and fair or red hair
  • Received radiation or x-ray treatments or taken immune suppressing drugs
  • Received more than 200 PUVA treatments

Discussions are under way about discontinuing PUVA treatment of psoriasis. The following are pro and con arguments about the procedure:

  • Opponents of PUVA argue that studies suggest a long-term risk for melanoma, starting about 15 years after treatment, particularly in people who receive more than 250 treatments.
  • Supporters of PUVA argue that it is not yet known whether the people who developed melanoma experienced sunburn during the procedures, or if they already had risk factors for skin cancers. If so, properly given treatments could still be considered safe for patients without risk factors. They also argue that PUVA is still the most effective treatment for severe psoriasis, and the alternatives are usually very powerful and relatively new drugs that may have even more serious side effects. Furthermore, adding retinoids may protect against skin cancers while increasing the treatment's effectiveness.

Protective Measures with PUVA Therapy

Review Date: 10/21/2010
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org)