What is psoriasis?
Psoriasis is a chronic disorder of the skin characterized by reddish, scaly patches of inflammation, most commonly affecting the elbows, knees, scalp, and/or groin. Psoriasis can be mild or severe. When it is severe, it can adversely affect functions of daily living, including work and social activities.
Psoriasis has been reported to affect approximately 2% of the world's population.
The treatment of psoriasis depends on its severity and location. Treatments range from local (cortisone cream application, emollients, coal tar, anthralin preparations, and sun exposure) to systemic (internal medications, including methotrexate [Rheumatrex, Trexall] and cyclosporine).
PUVA (psoralen and ultraviolet A radiation) treatment has been used for decades to treat severe psoriasis. In this "combination" therapy, the psoralen, taken internally, acts as a skin sensitizer. The "sensitized" skin affected by psoriasis can then be treated by ultraviolet A radiation.
PUVA and the risk of melanoma
Researchers at Harvard Medical School found that about 15 years after the first PUVA treatment, the risk of malignant melanoma increased more than fivefold, with the greatest risk observed in patients who received 250 treatments or more. Moreover, additional longer-term research confirmed this risk and indicated that the risk of melanoma increases with time in this patient population.
PUVA treatment is known to be highly effective for psoriasis and other skin conditions, allowing patients to resume normal life activities. PUVA has previously been shown to increase the risk for skin cancer. Melanoma, a fatal form of skin cancer if not treated, has now been added to the list of skin cancers that occur more frequently after a number of PUVA treatments.
Because of the potential cancer risks, doctors recommend that patients who receive long-term PUVA treatment should be carefully monitored throughout their lives. These patients should also report to their health care prpfessionals any peculiar skin abnormalities, including abnormally pigmented areas and skin that is changing color or size, itching, or painful.
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Stern, Robert S., Khanh T. Nichols, and Liisa H. Väkevä. "Malignant Melanoma in Patients Treated for Psoriasis With Methoxsalen (Psoralen) and Ultraviolet A Radiation (PUVA)." New England Journal of Medicine 336 (1997): 1041-1045.
Stern, Robert S. "The Risk of Melanoma in Association With Long-Term Exposure to PUVA." Journal of the American Academy of Dermatology 44.5 May 2001: 755-761.