Commentary
Women under age 50 years who regularly tanned indoors were at a twofold to sixfold increased risk of melanoma, compared with age-matched women who had not engaged in indoor tanning, according to a population-based control study.
The 681 individuals with melanoma, drawn from the Skin Health Study, a population-based case-control study evaluating the indoor tanning and the risk of melanoma, conducted in Minnesota, were diagnosed during 2004-2007. Of these, 68% were women; of the 654 controls, 68% were women. For the women younger than 30 years who had ever tanned indoors, compared with controls, the crude odds ratio of developing melanoma was 6.0; for women aged 30-39 years, the adjusted odds ratio was 3.5; and for women aged 40-49 years, the adjusted odds ratio was 2.3.
Indoor tanning was most common in 95% of women in the case group who were younger than 40 years, compared with 81% of controls of the same age (P less than .001), although “The median hours of routine and recreational sun exposure were fairly similar among females in both groups.” Women younger than age 40 years at diagnosis or reference age started tanning indoors at a median age of 16 years, compared with 25 years among women aged 40 years and older (P less than .001). The results were reported on line on Jan. 27 (JAMA Dermatol. 2016 Jan 27. doi: 10.1001/jamadermaool.2015.2938).
©The National Cancer Institute
“Given the substantial proportion of young women today who began indoor tanning as adolescents, this result is particularly concerning because their risk of developing melanoma in the future may be very high,” said DeAnn Lazovich, Ph.D., of the University of Minnesota, Minneapolis, and her associates.
Nearly all women who developed melanoma who were younger than 30 at diagnosis reported tanning indoors more than 10 times. In the older age groups (30-50 years), women were nearly three to four times more likely to develop melanoma if they reported tanning indoors more than 10 times. The strongest association between use of indoor tanning and melanoma was observed among women who developed melanoma on their trunk, with an odds ratio of 3.7.
In men, the strength of the association between indoor tanning and melanoma was variable. This was likely because of the small sample size for some age groups, Dr. Lazovich and her associates said. There was no clear pattern between the age at initiation of indoor tanning or a dose response in relation to development of melanoma in men depending on their age at diagnosis.
Melanoma rates generally are higher in women than in men until about age 50 years, but rates have been increasing in both younger men and women. In 1995, the rising rates seemed to diverge by sex, but in 2006, the incidence of melanoma started to increase more steeply in younger women than men, according to some sources.
This current analysis “provides evidence that indoor tanning is likely driver of diverging trends in men and women younger than 50 years in the United States,” the authors wrote.
The study was supported by National Institutes of Health grants. No conflicts of interest were reported.
