Indoor tanning may explain why U.S. melanoma rates are rising faster for women than for men, according to new research.
In a study of people under age 50 with melanoma - the deadliest skin cancer - the women who had tanned indoors were six times more likely than those who did not to have the cancer diagnosed before age 30.
That result is similar to those of an Australian study in 2011, said lead author of the new paper, DeAnn Lazovich of the University of Minnesota in Minneapolis. But the previous study did not separate men and women, she said by email.
"That almost all of the risk of melanoma related to indoor tanning was among women was surprising, as was the very strong association among the youngest women," Lazovich said of her study's results.
The researchers analyzed data on 681 adult patients diagnosed with melanoma between 2004 and 2007 and before age 50, and compared them to similar people without skin cancer between ages 25 and 49 years old. Women made up almost 70 percent of each group.
Nearly 80 percent of women said they had been indoor tanning, compared to 44 percent of the men.
Women under age 40 said they started indoor tanning at age 16, on average, compared to age 25 for the women ages 40 to 49. Younger women reported an average of 100 tanning sessions compared to 40 sessions for older women.
Women under 30 who had been indoor tanning were six times more likely than non-tanners to be in the melanoma group than in the comparison group. About a third of women diagnosed before age 30 had melanoma on their trunk, rather than the face or extremities, compared to 24 percent of women ages 40 to 49.
For all the women in the study, as the number of past tanning sessions increased, so did the risk of melanoma diagnosis, the study team reports in JAMA Dermatology.
"The World Health Organization, through its cancer branch (International Agency for Research on Cancer) declared artificial ultraviolet radiation from indoor tanning devices to be cancer-causing in 2009," Lazovich said.
The new results indicate that the more steeply rising rates of melanoma among women versus men younger than 50 years old are very likely due to indoor tanning use, she said. That's because of when the women started tanning indoors relative to the industry's popularity, the age at which they developed melanoma, the strength of the associations, and the propensity to develop melanomas on the trunk - which is typically exposed to ultraviolet radiation during a tanning bed session, but less so during outdoor activities in women.
Under age 50, melanoma rates are higher for women, but over age 50 rates are higher for men, she said.
"The study by Dr. Lazovich and her colleagues adds to an already large and growing body of evidence supporting the strong association between indoor tanning and melanoma, the deadliest form of skin cancer," said Gery P. Guy, Jr., of the Centers for Disease Control and Prevention in Atlanta, who coauthored an editorial alongside the new results.
"Melanoma is the most deadly type of skin cancer because it can spread to other parts of the body, including lymph nodes and distant organs," Guy told Reuters Health by email. "Melanoma causes over 9,000 deaths in the United States every year."
A tan is temporary, but an increased risk of melanoma is permanent, Guy added.
"Women under 40 who have tanned in the past may want to monitor their skin for any changes that could signal melanoma, so as to catch it as early as possible," Lazovich said. "They can certainly stop tanning indoors now, because our data show that the more tanning sessions, the greater the risk."
SOURCE: http://bit.ly/1OUgdQr and http://bit.ly/1SWfdPv JAMA Dermatology, online January 27, 2016.