Magazine article Drug Topics

Sunscreen: Help or Hindrance in Fighting Melanoma?

Magazine article Drug Topics

Sunscreen: Help or Hindrance in Fighting Melanoma?

Article excerpt

Does sunscreen help prevent melanoma? An epidemiologist at Memorial Sloan Kettering Cancer Center, New York City, cast light on the issue at a recent science conference.

Many experts advise people to wear sunscreen outdoors, because frequent sunburns have been linked to increased melanoma risk. But the deadly skin cancer continues to climb at alarming rates despite increased sunscreen use. The American Cancer Society estimates that 41,600 Americans will be diagnosed with melanoma and 7,300 will die from it in 1998.

Blanket advice to wear sunscreen as protection against melanoma is unwarranted, according to Marianne Berwick, M.D. At a Feb. 17 meeting of the American Association for the Advancement of Science, she reported that her study of 1,200 Connecticut residents, along with other epidemiologic research, revealed "no relationship between sunscreen use at any age and the development of melanoma skin cancer."

Genetics appear to overshadow other factors: People with numerous moles are six times more likely to get melanoma than those with only a few, and people with red or blond hair and light-colored eyes are six times more likely to get melanoma than those with darker complexions.

Of 10 studies, three-including Berwick's-found no link between sunscreen and the risk of melanoma. Two studies suggested that sunscreen prevents it; however, five suggested that the use of sunscreen might actually increase melanoma risk.

As a possible explanation for those five findings, Berwick observed that sun-sensitive individuals tend to use more sunscreen and are more likely to develop skin cancer regardless of sun exposure or sunscreen use. She cautioned that sun-sensitive people may be using sunscreen to stay out longer without burning when they would have otherwise sought shelter sooner. And complicating the assessment of connections between sunburns at an early age and melanoma risk was the fact that people often gave different answers at different times regarding their sunburn history.

Berwick also saw a rise in intermittent sun exposure and offered it as a possible explanation for increasing melanoma rates. "Chronic sun exposure may be protective for the development of melanoma, because the skin has adapted to the sun, having become thicker as it has tanned," she explained. On the other hand, intermittent exposure appears to increase risk.

Berwick concluded that sunburn, rather than causing melanoma, is a warning sign of excessive sun exposure-particularly among those genetically susceptible because of their skin type. …

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