How worried should I be about skin cancer now that summer is approaching and I’ll be spending time in the sun?
—Eva Haley-Locke, Seattle, WA
According to the U.S. Environmental Protection Agency (EPA), incidences of skin cancer in the United States have reached epidemic proportions, with one in five Americans now developing the disease in their lifetime. The National Cancer Institute reports that cases of melanoma, the most serious form of skin cancer, increased faster than any other cancer among Caucasians in the U.S. over a recent 20-year study period. The sometimes-fatal disease now accounts for three percent of cancers diagnosed in the U.S.
Incidences of melanoma in African Americans are much lower than in Caucasians due to the additional melanin, or pigment, in the skin, which offers some sun protection. However, dark skin is no guarantee against melanoma—and once African Americans are diagnosed with melanoma, studies show that their long-term survival is significantly lower than that of Caucasians: 58.8 percent compared to 84.8 percent.
Meanwhile, non-melanoma skin cancers are on the rise, too. Every year, more than a million Americans develop non-melanoma skin cancer, and more than 1,900 die from the disease, according to EPA statistics. But non-melanoma skin cancers have a cure rate as high as 95 percent if detected and treated early.
Skin cancer is triggered by exposure to the sun”s ultraviolet-B (UV-B) radiation. Luckily, the Earth”s ozone layer absorbs most UV-B radiation before it reaches the surface. However, the recent thinning of the ozone layer due to the emission of chlorofluorocarbons (chemicals used to propel aerosol sprays and keep refrigerators and air conditioners cool) may have further increased everyone”s exposure to UV-B radiation.
Fortunately, 183 countries, including all the major industrial powers, have agreed to phase out these chemicals by 2015 according to the terms of a 1987 treaty known as the Montreal Protocol. The signatories to the treaty are optimistic that the phase-out should restore the ozone layer to its normal thickness over the course of several decades.
Interestingly, some researchers don’t believe that current melanoma increases are related to the thinning ozone layer, as the disease can take several decades to develop, whereas ozone depletion is a more recent phenomenon. “Recent increases in rates may just reflect better reporting, or the popularity of suntans in the 60″s and “70”s,” says University of Colorado biochemist Robert Parson.
Nevertheless, UV-B exposure remains a risk. People should protect themselves by wearing hats, sunglasses and sunscreen, and avoiding extended sun exposure. Many dermatologists believe there may be a link between childhood sunburns and melanoma later in life; so strong sunscreen (SPF 30 or higher) should be applied to kids before they head off to the beach.
CONTACTS: EPA SunWise Program, www.epa.gov/sunwise ; National Cancer Institute, www.nci.nih.gov ; Montreal Protocol, www.unep.org/ozone/Montreal-Protocol/Montreal-Protocol2000.shtml .