Genital tumors among men with psoriasis exposed to psoralens and ultraviolet A radiation (PUVA) and ultraviolet B radiation

Article Abstract:

The first clearly traced relationship between environmental exposure and development of cancer was achieved by Percival Pott in 1775. While Pott found that cancer of the scrotum could be caused by tar pitch, evidence has now accumulated that the same cancer can be caused by a treatment for psoriasis which has been in use since 1975. A total of 1,380 patients received psoralens and ultraviolet A radiation (PUVA) treatment for psoriasis in 1975 and 1976. PUVA consists of treatment with methoxsalen (8-methoxypsoralen), a photosensitizing compound, and ultraviolet A illumination. Ultraviolet A is light of wavelength from 320 to 400 nanometers; it is a longer and less energetic wave than ultraviolet B, which extends from 290 to 320 nanometers. Both forms of ultraviolet are known to increase the risk of skin cancer; a review of the 892 men among the patients who received PUVA therapy reveals that the risk to the penis and scrotal sac is even greater than the risk of skin cancer in general. Of the 892 male patients, 14 developed a total of 30 squamous cell carcinomas of the genitals. For those receiving the highest dose of PUVA, this represents a risk almost 300 times the risk of white males in general. Furthermore, while the ratio of squamous cell carcinomas of the head and neck to those of the genitals is 83 to 1 in the general population, the ratio was only 3 to 1 in the study population. This indicates a particular susceptibility of the genitals, which may be due to the relative inability of this region to develop protective tanning. When equivalent doses of PUVA were controlled for in the statistical analysis, it was found that the shorter wavelength ultraviolet B alone also had an independent influence, increasing the risk of genital cancer roughly fourfold. Although squamous cell carcinoma of the vulva is more common in the general population than are tumors of the penis, only one case was seen among the women in the PUVA study, suggesting that the greater exposure of the male genitalia is a key factor in the risk of genital cancer. Since many individuals, including over 1 million individuals a day in tanning salons, have some degree of ultraviolet exposure for therapeutic or cosmetic reasons, extra care should be taken to shield the genitalia. (Consumer Summary produced by Reliance Medical Information, Inc.)

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Phototherapy and photochemotherapy

Article Abstract:

Healthful benefits have traditionally been ascribed to the rays of the sun. More recently, ultraviolet light has been applied to the treatment of a number of skin disorders, including mycosis fungoides, which is a T-cell lymphoma (tumor of the lymphatic system) that affects the skin. The primary use of phototherapy, however, is in the treatment of psoriasis, in which the ultraviolet light helps destroy some of the hyperproliferative cells characteristic of the disease. Treatment usually consists of exposure to ultraviolet B, which are the higher energy rays, or exposure to ultraviolet A, in combination with a photosensitizing chemical such as methoxsalen. It is worthy of note that the ancient Egyptians used this treatment for vitiligo from 2000 to 1200 B.C. The sun provided ample ultraviolet, and the photosensitization was provided by plants which we now know to contain methoxsalen and other psoralens. Although these treatments are extremely valuable in dermatology, an article in the April 19, 1990 issue of The New England Journal of Medicine presents evidence that this exposure to the ultraviolet A/psoralen combination, or exposure to ultraviolet B, drastically increases the risk of cancer of the penis and scrotal sac. This evidence clearly indicates that this area should be protected when it is not affected by psoriasis. New ways to retain the effectiveness of the treatment while reducing the risk of cancer are being explored. Promising among these is the combination of the treatment with retinoids such as etretinate and aciretin. These compounds accelerate the clinical response, thereby reducing the necessary UV exposure. Furthermore, these compounds are believed to have anticarcinogenic effects and may act directly to prevent the development of cancer among these patients. (Consumer Summary produced by Reliance Medical Information, Inc.)

Health aspects, Retinoids, editorial

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Malignant melanoma in patients treated for psoriasis with methoxsalen (psoralen) and ultraviolet A radiation (PUVA)

Article Abstract:

People with psoriasis who receive long-term treatment with psoralen and ultraviolet A radiation may have an increased risk of melanoma. Psoralen and UV-A radiation (PUVA) is a very effective combination treatment for psoriasis. However, in a long-term study of 1,380 patients with psoriasis who began PUVA treatment in 1975-1976, researchers identified an increase in the incidence of melanoma after 1990. The incidence of melanoma 15 years after treatments began had increased 68% compared to the incidence in the first 5 years. Seven of the patients developed melanoma after 1991, a rate five times greater than normal.

Drug therapy, Ultraviolet radiation, Melanoma, Photochemotherapy

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