Association between Indoor Tanning and Melanoma Confirmed in New Meta-Analysis
Toronto, Ontario—Going to more than 10 indoor tanning sessions over a person’s lifetime is associated with a 34% increased risk of developing melanoma, according to a new meta-analysis presented at the 2014 Canadian Dermatology Association annual meeting.
“Clinicians should continue to educate patients on the harms of indoor tanning and encourage its cessation,” said lead investigator Sophia Colantonio, MD, MPH, of the Division of Dermatology, Department of Medicine, University of Ottowa, Ontario, Canada, in an e-mail to Value-Based Cancer Care.
These results confirm previous studies showing an increased rate of skin cancer among people who use tanning beds, and add new information as well. The other parameters of the study showed:
- A 23% increased risk for melanoma among North Americans who had ever used indoor tanning compared with those who had never used it
- People who first used indoor tanning before age 25 years had a 35% risk of developing melanoma compared with an 11% increased risk for those who started indoor tanning later in life.
“We feel this is an important area of research, and further high-quality studies such as prospective cohort studies will yield more valid results that clinicians can use to counsel their patients about the risks of indoor tanning and promoting tanning bed avoidance,” Dr Colantonio said.
The meta-analysis of the literature on indoor tanning included 37 cohort studies, case-control, or cross-sectional studies that were published in any language in peer-reviewed journals up to August 14, 2013. The team of researchers focused the meta-analysis on the 31 studies that had risk estimates—13 provided crude odds ratios and the other 18 had adjusted odds ratios. Overall, the 31 studies included 14,956 cases of melanoma and 233,106 controls.
The results showed a significantly increased risk of melanoma associated with people who had ?10 tanning sessions, lived in North America, and started indoor tanning before age 25 years.
Furthermore, a 61% increased melanoma risk was associated with using tanning beds for more than 1 year compared with having never used tanning beds, and a 37% increased risk among those who used tanning beds for less than 1 year compared with never-users.
The researchers also found that newer tanning bed bulb technology, which emits larger doses of long-wave ultraviolet A, increases the risk of melanoma: there was a 22% increased risk of melanoma among people who had ever used indoor tanning versus people who had never used indoor tanning after the year 2000, and only a 12% increased risk with ever use versus no use before 2000.
However, the investigators noted that the quality of the studies ranged from poor to mediocre, and several of the subgroup analyses involved heterogeneous studies.
“This meta-analysis has highlighted the poor to mediocre quality of evidence available on this topic, mainly because the majority of studies used a case-control design, which is prone to several biases,” the investigators noted in their article, which was simultaneously published in the Journal of the American Academy of Dermatology (Colantonio S, et al. 2014;70:847-857). “Future research should consider prospective study designs in large population cohorts,” they added.