Science and Health

Why skin cancer is on the rise

(Agencies)
Updated: 2010-06-22 09:57

For years and years now, millions of sun worshippers across the country would hit the beaches during summer to work on the perfect, golden tan. However, the advent of indoor tanning salons now allows Americans to sport a sun-kissed look year-round. And as more and more people pursue a perpetual summer-style tan, dermatologists have begun noticing a significant rise in skin cancer incidents, especially among young women.

Melanoma, the deadliest form of skin cancer, still makes up just 3 percent of all skin cancers, and results in about 8,000 deaths a year, according to the National Cancer Institute. But three factors have doctors alarmed: The rates of this cancer are rising; it has become the most common cancer for young people; and many of the cases result from the preventable, but addictive, behavior of indoor suntanning.

"In the last few decades, it's certainly been on the rise. And some people think that may be a result of behavior, and UV exposure," said Jennifer Stein, an assistant professor of dermatology at New York University's Langone Medical Center. "This is a very serious cancer, and this is a behavior that's preventable."

Tanning and cancer go hand-in-hand

Without tanning beds, soaking up the rays was limited to clear days in the summer. The invention of the tanning bed changed that, and throughout the 1990s, the rapid proliferation of tanning salons provided venues for millions of people to sunbathe regardless of weather, season, or time of day.

Since 1992, the indoor tanning industry has grown five-fold, with 28 million indoor tanners in the United States supporting a billion-dollar-a-year business, said Maria Tsoukas, an assistant professor of dermatology at the University of Chicago Medical Center.

During that same period, melanoma rates have increased by 2 percent in the general population, Stein said. Amongst young women, who make up 71 percent of tanning salon customers, incidents of melanoma have increased by 2.2 percent, Stein said. Over that time, skin cancer also became the most common form of cancer for Americans ages 25-29, a group that traditionally shows very low cancer rates, Stein said.

"We see a surprising number of young women coming in with melanoma, and a lot of them say they've used tanning beds," Stein told LiveScience.com. "By far, by far, the majority of users of indoor tanning beds are young women."

While some dermatologists believe that other factors, such as increased UV exposure resulting from the hole in the ozone layer, contribute to the rise in melanoma rates over the last 18 years, the irrefutable link between indoor tanning and melanoma makes tanning beds the prime suspect, Tsoukas said.

In a recent study conducted by researchers at the University of Michigan, frequent tanning bed users proved three times more likely to develop melanoma than non-users, and subjects that used tanning beds for any amount of time showed a 74-percent higher rate of melanoma than non-users, according to research published online May 27 in the journal Cancer Epidemiology, Biomarkers and Prevention.

That study did not investigate the percentage of indoor tanners who developed melanoma, rather showing the difference between users and non-users.

How tanning causes cancer

Indoor and outdoor tanning can be dangerous, because the same ultraviolet radiation that provokes a tan also damages DNA. In fact, exposure to the mid-day sun can produce as many as 40,000 DNA errors an hour, said Regina Santella, a professor of environmental health sciences at Columbia University's Mailman School of Public Health in New York.

The UV light causes the DNA molecule thymine to bind to adjacent thymine molecules in a manner that renders both molecules unreadable during transcriptions, Santella said. Transcription is a step in which the body reads the DNA instructions the cell will later follow. When those thymine errors occur in areas of DNA that regulate cell growth, skin cancers like melanoma can begin to develop, Santella said.

Most times, skin cells rapidly repair most of those 40,000 errors, but over time repeated errors can cause cancer or other problems.

Tanning is actually the body's response to that damage, with the darker color produced by skin adding an additional layer of protection for the DNA, Stein said. However, when the body produces the hormone that initiates tanning, it also produces a secondary molecule in the endorphin family, said Steve Feldman, a professor of dermatology at the Wake Forest University Baptist Medical Center.

Endorphins are chemicals that transmit feelings of pleasure and happiness. In effect, exposure to UV radiation gets tanning bed users high, Feldman said. And like any high, tanning can become addictive.

In 2005, Feldman conducted a study where he gave volunteers endorphin-blocking chemicals before they used a tanning bed. The study aimed to test whether frequent tanning salon customers would enjoy the experience as much if their bodies didn't produce endorphins. They didn't. And even before the frequent tanners used the tanning bed, they showed signs of physical addiction to tanning.

"When we started doing the experiments, the first couple volunteers got sick, and we said 'Hey, that's unexpected,'" Feldman told LiveScience. "We were putting them into withdrawal."

Tan responsibly

With studies proving that tanning bed use causes both addiction and cancer, many dermatologists have begun comparing the practice to other forms of drug abuse like drinking and cigarette smoking, Feldman said. And much like with smoking and drug abuse, doctors have told their tan-loving patients to "just say no."

"There is no point to it. Someone wants to look darker? Gimme a break. For cosmetic reasons, people risk getting a fatal cancer. To me, it's a public health hazard because it has no upside," Santella said. "Don't go to skin tanning salons. Simple as that."

Others advocate that tanning salon patrons take an approach more like drinking alcohol, with moderation and responsibility mitigating the long-term health effects, Feldman said.

"We see the cancer patients, but there are millions of people tanning, and considering the number of people doing it and not getting cancer, it's probably not the first problem we need to solve in America," Feldman said. "If a woman comes in, and I see cigarettes in her bag, I'll tell her to stop smoking before I tell her to stop tanning. Lung cancer is considerably worse."

But those approaches only tackle the physical side of tanning without getting to the root problem that drives millions of Americans, young women in particular, to engage in a behavior they often know raises their risk of a deadly disease, Stein said. To fix the social pressures behind the rise in this largely preventable cancer, America might need to refine its idea of beauty.

"I've met people who said they couldn't stop tanning. They wanted to stop, but couldn't. They liked the way it felt and they felt pressure from their friends," Stein said. "I think we really need to change that notion in this country that looking tan means looking healthy, because we know that tans are not healthy."