点击显示 收起
April 22, 2009 (Denver) -- Looks can be deceiving. New genetic research suggests that dark-haired people who do not sunburn easily may be at risk for potentially deadly skin cancer, too.
"There's been this whole idea of duality between light-complexioned people with red hair and a proclivity to burn in the sun as one group at high risk of melanoma, and a second group with dark hair who tan well and do not have to worry about being in the sun as a second group at low risk," says Peter Kanetsky, PhD, assistant professor of epidemiology at the University of Pennsylvania.
The new research suggests that even people who "have not been severely harmed by the sun may still be at increased risk of melanoma," he tells WebMD.
The findings were presented at the annual meeting of the American Association for Cancer Research.
Kanetsky and colleagues identified variants in the melanocortin-1 receptor (MC1R), a gene discovered in the mid-1990s that is associated with human pigmentation. Their study involved 779 people with melanoma and 325 healthy people.
Overall, the presence of certain genetic variants in MC1R was associated with a more than twofold risk of melanoma, but this risk was largely confined to those patients who had dark hair and dark eyes and tanned easily.
If people had dark hair and also inherited certain MC1R genetic variants, their risk for melanoma increased 2.4-fold. MC1R variants were associated with a 3.2-fold increased risk among those with dark eye color, an eightfold increased risk among people who did not freckle, and a 9.5-fold increased risk among people who tanned quickly without burning.
"In people with light skin, MCIR variants had null or little effect," Kanetsky says. About 10% of melanomas in dark-complexioned people may be associated with MCIR variants, he says.
A screening test for MC1R is not yet available.
Melanoma accounts for less than 5% of skin cancer cases but causes the majority of skin cancer deaths. In 2008, more than 62,000 new melanomas were diagnosed in the U.S., and an estimated 8,420 Americans died from the disease, according to the American Cancer Society.
Also at the meeting, Texas researchers reported that genetic variations in the body's inflammation pathway may lower the likelihood of recurrence and improve the chance of survival in people with bladder cancer.
"The idea is to develop a blood test for predicting recurrence," says Hushan Yang, PhD, a postdoctoral fellow at the University of Texas M.D. Anderson Cancer Center in Houston.
The American Cancer Society estimates that 68,810 new cases of bladder cancer were diagnosed in 2008. Yang and colleagues studied people with non-muscle invasive bladder cancer. Most cases of bladder cancers have not invaded the bladder muscle.