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Darker skin doesn't mean melanoma immunity

Melanoma is on the rise among certain groups of dark-skinned Floridians, new research shows.
/ Source: Reuters

NEW YORK (Reuters Health) - Melanoma is on the rise among certain groups of dark-skinned Floridians, new research shows.

And while it's not clear why from the current study, the study does provide an important take home message, according to Dr. Robert S. Kirsner of the University of Miami Miller School of Medicine: "Just because you have darker skin pigmentation, whether you're Hispanic or black, does not make you immune to skin cancer," he told Reuters Health.

Melanoma remains much rarer among blacks and Hispanics than among whites, which helps explain why public health efforts to prevent melanoma chiefly target the light-skinned among us.

In the current study, for example, in 2004 there were about 26 cases of melanoma diagnosed for every 100,000 persons per year among US whites, compared to 4 cases for Hispanics and less than 1 case for non-Hispanic blacks.

Nevertheless, non-whites with melanoma are diagnosed later, and are thus actually more likely to die from the disease, Kirsner and his team point out in the Archives of Dermatology.

"It's picked up later and a lot of this is really felt to be due to decreased detection and screening," Dr. Melody Eide, a staff physician-scientist at Henry Ford Hospital in Detroit who has studied ethnicity and melanoma but was not involved in the new study, told Reuters Health.

To determine whether trends in melanoma incidence in Florida might differ from those in the US as a whole, Kirsner and his team compared data from the Florida Cancer Data System and the national cancer database for 1992 through 2004. Florida is a bellwether for the rest of the country, Kirsner pointed out, given its diverse population (about one-fifth of Floridians are Hispanic, and around 16 percent are black) and high levels of ultraviolet radiation.

Results showed that Hispanic men living in Florida were 20 percent more likely to develop melanoma than Hispanics in the US as a whole. Their rate of melanoma was rising at the same rate -- about 3 percent per year -- as it was in whites nationally.

Hispanic women in Florida, on the other hand, were actually 30 percent less likely to develop melanoma than the Hispanic women included in the national database. The rate of melanoma among non-Hispanic black women was 60 percent higher for Floridians compared to the US as a whole. Black men in Florida had the same melanoma risk as black men across the US. White Floridians actually had lower rates of melanoma compared to whites nationwide.

"These findings may suggest an emerging public health concern in race/ethnic subgroups residing in Florida, a geographic location with heavy ultraviolet radiation exposure," Kirsner and his colleagues write.

Florida has a very diverse population of Hispanics, with relatively light-skinned Cubans predominating, the researchers note; this could help explain the higher rate of melanoma among the state's Hispanic men.

Lumping all Hispanics into a single category when studying melanoma incidence is problematic, Kirsner noted. "Not all Hispanic people are from the same country, and they don't have the same skin type," he said.

There needs to be better awareness among non-white patients -- and their doctors -- that dark skin doesn't confer immunity to melanoma, according to Kirsner. People of any color should watch for skin growths that meet any of these criteria, he added: asymmetrical; irregular, nicked or notched borders; multiple colors; the size of a pencil eraser or larger; or growths that are evolving or changing.

"If you have one it doesn't mean you have melanoma, but it does mean perhaps that you should have it evaluated to make sure that nothing's going on," Kirsner said.

And regardless of whether you have light or dark skin, Kirsner said it's best to follow "sun-smart" behaviors like seeking out shade, covering up, avoiding the midday sun, and wearing sunscreen.

"It's really important that people know that regardless of their skin color there is a risk of melanoma," Eide agreed.