University of Oslo, Faculty of Medicine
Melanoma is the most dangerous type of skin cancer with the strongest increase in incidence in the last decade, and the incidence rates have never been as high as in 2014 (www.kreftregisteret.no).
Now there are about 2,000 new cases of melanoma each year in Norway.
The World Health Organization based International Agency for Research on Cancer has classified UV-emitting tanning devices as "carcinogenic to humans" in 2009 (www.iarc.fr).
New evidence on the damaging effect of sunbeds
The study followed 141,000 Norwegian women for the average of 14 years.
Women who had 30 or more indoor tanning sessions were at 32% increased risk of melanoma compared to never-users.
In addition, women who started indoor tanning before age 30 were on average 2 years younger at melanoma diagnosis than never-users.
These associations remained significant after controlling for age, birth-cohort, ambient UV of residence, hair color, skin color, and cumulative number of sunburns and sunbathing vacations.
Public health importance
Modern sunbeds emit six times more UVA and twice as much UVB as Oslo summer sun.
The findings of this study have important implications for public health, as it shows that sunbed use increases the burden of melanoma in societies by both increasing the number of patients and decreasing the age at diagnosis.