In a study of 1,167 melanoma cases and 1,101 people without melanoma (controls), 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.
The findings were published in Cancer Epidemiology, Biomarkers & Prevention.
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.”
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.