Indoor ultraviolet (UV) tanners are 74 percent more likely to develop melanoma than those who have never tanned indoors. Additionally, the more time a person has spent tanning indoors, the higher the risk. Melanoma is the deadliest form of skin cancer, killing approximately 8,650 Americans in 2009. "We hope that these findings, along with what we already know about the risks of indoor tanning, will keep people from using tanning beds," said Allan C. Halpern, MD, MSc, Chief of the Dermatology Service at New York City's Memorial Sloan Kettering Cancer Center, and Vice President, The Skin Cancer Foundation.
In a study of 1,167 melanoma cases and 1,101 people without melanoma (controls) appearing in Cancer Epidemiology, Biomarkers & Prevention, researchers, led by DeAnn Lazovich of the University of Minnesota, found that almost 63 percent of the melanoma patients but just over 51 percent of the control group had tanned indoors. Ultraviolet radiation from tanning machines is cancer-causing to humans, according to a 2009 report released by the International Agency for Research on Cancer (IARC), affiliated with the World Health Organization. The IARC also includes solar radiation in its list of the most dangerous types of cancer-causing substances.
"This excellent study addresses several of the weaknesses and critiques of prior case control studies assessing the melanoma risk associated with UV tanning devices," said Dr. Halpern. "The new data strongly support the conclusions of the IARC."
Tanning frequency directly influenced melanoma risk in the Minnesota study. People who had tanned indoors for more than 50 hours (more than 100 sessions, or 10 or more years) were between 2.5 and 3.0 times more likely to develop melanoma than non-indoor tanners. "We hope this additional data will motivate the FDA to expedite appropriate regulation of these devices," added Dr. Halpern. Currently, tanning machines are considered Class I medical devices, making them subject to few regulations and little oversight. In March, a US Food and Drug Administration (FDA) advisory panel unanimously recommended that the FDA upgrade its medical device classification of tanning machines to better reflect the dangers they pose to users' health.
The study did not find that the age at which indoor tanners begin the practice is as influential as previously thought. In 2006, a meta-analysis (study of multiple studies) found that people who began tanning before age 35 had a 75 percent higher risk of developing melanoma. But, according to the authors of the study, "our analysis indicates that early age exposure is most likely a marker for cumulative exposure," meaning that the younger a patient was when s/he started tanning, the more time s/he has had to accumulate hours of UV radiation exposure.