LOS ANGELES ? Although there is little argument about the sun's powerful role in basal-cell and squamous-cell carcinoma, the influence of solar radiation in malignant melanoma etiology is less clear cut.
LOS ANGELES, June 2 ? Although there is little argument that the sun plays a powerful role in basal-cell and squamous-cell carcinoma, the influence of solar radiation in malignant melanoma etiology is less clear cut.
Indeed, some researchers have contended that a person's genetic makeup overshadows sun exposure as the most important factor in the genesis of melanoma, said dermatologist Elisabeth K. Shim, M.D., and colleagues, at the University of California Keck School of Medicine here.
In the April issue of Dermatology Surgery, Dr. Shim and colleagues reviewed 100 studies on melanoma and the sun published over the last two decades.
Key evidence against the sun and favoring a genetic explanation included:
?Likely, there is a complex interaction among genetic factors, the environmental factor of sun exposure, and other possible factors, which lead to melanoma development,? the California team said.
?Nonetheless, overall, there is a large amount of evidence from epidemiologic, genetic, and animal studies suggesting that sun exposure plays a large contributing role in the development of most cutaneous melanomas,? they added.
?It seems prudent to continue to recommend lifelong sun-protective measures to patients,? they advised.
While agreeing with the California researchers, Martin A. Weinstock, M.D., Ph.D., a professor of dermatology at Brown University in Providence, R.I., noted that there are some arguments against blocking the sun out of one?s life to too great a degree. Dr. Weinstock chairs the American Cancer Society?s skin cancer advisory group.
First, persons who spend more time outdoors tend to be physically active, Dr. Weinstock said. Even though many of us work out in indoor gyms, outdoor activities remain a significant part of our overall physical activity, which is important for overall health, he said.
Second, people need sunlight on their skin in order to produce vitamin D, Dr. Weinstock said. This vitamin is believed to help maintain bones health by regulating serum levels of calcium and phosphorous. However, for those with limited sunlight exposure, such as those living at higher latitudes, vitamin D can also be obtained from dietary supplements, he said.
When it comes to sun protection, the cancer society promotes the ?slip, slop, slap, and wrap? approach, Dr. Weinstock said, as in slip on a shirt, slop on sunscreen (with a sun protection factor of at least 15), slap on a hat, and wrap on sunglasses to protect the eyes from ultraviolet light.