People who use indoor tanning beds to darken their skin are 74% more likely to develop melanoma than non-users, according to a Minnesota study of 1,167 melanoma cases and 1,101 controls. Melanoma risk increased in a dose-response manner according to tanning bed exposure (measured by total hours, sessions, or years) regardless of the age at which tanning began.
Indoor tanning is an artificial source of intermittent ultraviolet (UV) radiation. In this study, people who had used indoor tanning beds for more than 50 hours (more than 100 sessions, or 10 or more years) were more likely to develop melanoma than those who had never used indoor tanning beds. The study, “Indoor Tanning and Risk of Melanoma: A Case-Control Study in a Highly Exposed Population,” appears in the American Association for Cancer Research journal Cancer Epidemiology, Biomarkers & Prevention (2010;19:1557-1568).
This is the largest study to date on indoor tanning bed use and melanoma risk, lead author DeAnn Lazovich, PhD, Associate Professor of Epidemiology and Community Health in the University of Minnesota's School of Public Health and Masonic Cancer Center, noted in an AACR telebriefing. “We found a stronger association than previous studies.”
She added that the data were particularly robust for melanomas of the trunk, and that each type of tanning device studied carried a risk, such that none can be considered safe.
Increasing Incidence of Melanoma
Between 1997 and 2006, US melanoma incidence increased 2.2% annually among Caucasian males and 2.1% annually among Caucasian females, and melanoma now ranks first among men and second among women on the list of the 10 most common cancers in Caucasians. In 2009, melanoma claimed the lives of about 8,650 Americans, according to the Skin Cancer Foundation.
In 2009 the International Agency for Research on Cancer (IARC) stated that UV radiation from indoor tanning machines is carcinogenic to humans, Allan C. Halpern, MD, Chief of the Dermatology Service at Memorial Sloan-Kettering Cancer Center and Vice President of the Skin Cancer Foundation, noted at the same briefing.
“We do know that tanning beds are part of the problem” in the increasing incidence of melanoma. Many of our patients still desire the aesthetics of a tan.”
Previous Studies Had Unanswered Questions
He praised the new study, stating that previous studies on indoor tanning and melanoma left unanswered questions “that were not answered to our satisfaction.”
Dr. Halpern said he hopes this new study will be helpful to the US Food and Drug Administration in moving forward with stronger regulations governing the use of indoor tanning beds. (The FDA is considering a ban on indoor tanning use among teenagers.)
In addition, he said, “I think it very much strengthens our hand” as physicians in persuading patients that a tan from an indoor tanning device might carry a price that is much too high to pay.
Asked by OT if exposure to indoor tanning beds can be considered more dangerous than exposure to natural sunlight, Dr. Lazovich said, “There are elevated risks associated with ultraviolet radiation regardless of the source of that radiation.” In the discussion section of her study, she and her co-authors note that they did not find lifetime routine sun exposure or sun exposure via recreational outdoor activities or occupations to be associated with melanoma risk, a finding which strengthens the conclusion that people who use indoor tanning beds routinely are at higher risk than non-users.
Dr. Lazovich's study observed a higher melanoma risk for so-called high-speed or high-pressure indoor tanning devices than for conventional indoor tanning beds. What is not clear, she said, is whether this higher risk reflects higher exposure to UVB from high-speed devices or higher exposure to UVA from high-pressure devices. She noted that indoor tanning beds differ in the amount of UVA and UVB they emit.
Asked during the telebriefing whether her study could be considered biased because the tanning bed industry considers her an advocate for stopping use of their devices, Dr. Lazovich said, “I am not an advocate. I am a cancer researcher.” She noted that all of her research has been peer reviewed by the National Institutes of Health—from which she has received research funding—or other reputable scientific groups, and that she has received no industry funding.
Asked about concerns that people who do not get enough UV exposure may develop vitamin D deficiency—which could lead to an increased risk of cancer and other diseases—Dr. Lazovich said, “I'm particularly interested in vitamin D and cancer.” But, she said, “I think it's really important to weigh the risks vs. the benefits” of exposure to ultraviolet light. She noted that people who are concerned about vitamin D deficiency can take a supplement. “In my mind it's an easy choice.”
Asked if people should avoid UV light completely, she said, “We're really at the beginning of understanding vitamin D and health issues.” She said she is awaiting the results of careful research studies on vitamin D and health.
Dr. Halpern added that for many people, by dint of where they live or their darker skin color, they can't get enough vitamin D by skin exposure anyway.
‘Overcomes Some of Shortcomings of Previous Studies’
“I think that this study is a very well-done study that overcomes some of the shortcomings of previous studies,” commented Electra Paskett, PhD, MPH, Associate Director for Population Sciences at the Ohio State University Comprehensive Cancer Center, Arthur G. James Cancer Hospital and Richard J. Solove Research Institute, who also participated in the AACR telebriefing.
She noted that 35% of girls age 17 have used indoor tanning beds, and that these devices are an underappreciated cancer risk factor. Among some teenage girls, sporting a tan “has become sort of a fashion statement,” and the girls may not realize that melanoma risk increases in a dose-response manner and that melanoma can occur in younger age groups. Thus, she said, “To really impact this behavior [indoor tanning], we are going to have to go to changing social norms.”
She called on parents and teachers to help persuade teenagers not to cultivate a tan.
“I do a lot of behavioral intervention studies…I would use the model that we've used with tobacco,” Dr. Paskett said.
“Just as we ask about tobacco use, we should be asking about tanning bed use. This has all been done for tobacco, we're trying to do it for obesity,” and now it needs to be done for indoor tanning beds. Because habitual use of tanning beds is not addictive, as is tobacco use, changing societal norms regarding indoor tanning bed use should not be as difficult as getting people to stop smoking, she said.