On average, indoor ultraviolet (UV) tanners are 74 percent more likely to develop melanoma than non-tanners, according to a new study; and the more time a person has spent tanning indoors, the higher the odds of developing the disease. The researchers also discovered that the type of tanning machine used affects melanoma risk — some tanners were 4.44 times as likely as non-tanners to develop melanoma. Melanoma is the deadliest form of skin cancer, killing approximately 8,650 Americans in 2009.
In a study of 1,167 melanoma cases and 1,101 people without melanoma (the control group) appearing in Cancer Epidemiology, Biomarkers & Prevention, researchers led by DeAnn Lazovich, PhD, MPH, an associate professor at 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. UV 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.
Frequency Plays an Important Role
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.
Users of high-pressure tanning devices, which primarily emit UVA radiation, had 4.44 times the melanoma risk of those who had never tanned indoors, while users of high speed/high intensity tanning devices (which emit UVB as well as UVA radiation) had 2.8 times the risk. Nonetheless, the authors were quick to point out that “no device could be considered ‘safe,’” and “All indoor tanning devices are harmful.”
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 Minnesota 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.