U study links indoor tanning to melanoma

People who use tanning beds frequently have up to three times the risk of developing the deadliest form of skin cancer -- no matter how old they are when they start -- according to a study published Thursday by researchers at the University of Minnesota.

The study, based on the experience of more than 2,000 Minnesotans, is the most definitive link yet between exposure to artificial ultraviolet light and melanoma, experts say, and could influence the Food and Drug Administration (FDA) in a pending decision on whether to tighten regulation of tanning salons. A ban on indoor tanning for teenagers is even possible.

"This could affect how the FDA will rule," said Dr. David Fisher, a melanoma expert and a professor of dermatology at Harvard University, who was not involved in the study.

The indoor tanning industry took issue with the findings Wednesday, even before the study was published online Thursday by the journal Cancer Epidemiology, Biomarkers and Prevention.

"There are many more studies that have failed to find a relationship," said John Overstreet, executive director of the Indoor Tanning Association. "They are trying to influence the FDA and I think that's not right."

DeAnn Lazovich, an epidemiologist and lead author of the university's study, said it proves tanning beds "are an important risk factor than can be avoided."

Fisher said he wished the research had been made public in March, when an expert panel met to debate increasing the federal regulation of indoor tanning. Many experts who testified urged the panel to recommend more stringent rules and to restrict tanning by minors. The FDA has not yet made a decision.

Like the sun, lamps that emit ultraviolet radiation have long been considered a risk factor in all three kinds of skin cancer. The most dangerous is melanoma; when it spreads from the skin to other parts of the body it is lethal 97 percent of the time -- usually within six months.

Concern about the safety of indoor tanning has accelerated in the past two years, since the Centers for Disease Control and Prevention (CDC) reported that between 1973 and 2004 the number of annual cases of melanoma among young women nearly tripled, to 13.9 per 100,000 people. During the same period, melanoma rates among young men leveled off, leading many to question whether tanning beds were playing a part. Women are seven times more likely to use them than men, according to national data.

Last year the World Health Organization upgraded indoor tanning devices from probable carcinogen to known carcinogen, along with tobacco and asbestos. It was inspired by research that found the risk of melanoma increased by 75 percent among people who started using tanning beds before age 35.

But the organization was unable to account for the role of other risk factors, such as skin type and outdoor exposure.

Lazovich's study was designed specifically to measure the effects of indoor tanning, not UV radiation in general, said Richard Gallagher, a cancer epidemiologist with the British Columbia Cancer Agency in Canada, the province's leading cancer research center and hospital.

Clear cause and effect

Lazovich and her co-authors surveyed 1,167 people in Minnesota who were diagnosed with melanoma between the ages of 25 and 59, and 1,101 who were without cancer.

She found that 63 percent of those with cancer had used tanning beds at some point in their lives, compared with 51 percent in the second group. That represented an increased risk of 74 percent, she said.

Unlike previous studies, the researchers accounted for other risk factors such as sun exposure, age and skin type.

But what was most telling about her findings, other scientists said, is that they linked increased use of tanning beds to an increased likelihood of developing cancer -- a clear indication of cause and effect.

"In every single way we looked at it, we saw an increase," Lazovich said.

Overstreet of the tanning association disputed the findings. He said that Minnesotans are largely of northern European stock, and their fair skin puts them at greater risk of cancer.

"There are millions who don't have to worry about the same amount of risk," he said.

Lazovich, however, said that skin type was factored into her analysis.

Fisher said he's concerned that unless regulations change soon, mortality rates from melanoma will start rising as well. But so far, he said, that hasn't happened.