by Sara E. West, MDa, Kari L. Martin, MDb, and Susan K. Ailor, MDa
a University of Missouri
b Medical College of Wisconsin
Published in Missouri Medicine, the journal of the Missouri State Medical Association, May/June 2012
Incidence rates of melanoma continue to rise, especially in young women, despite the enormous body of evidence that identifies ultraviolet radiation as a skin carcinogen. It is time for a change in societal norms, an increase in counseling of young adults about the risks of indoor tanning facilities, and to prevent young adults from tanning by introducing new legislation.
The title at first glance may seem a bit dramatic, but it is the reality of teen tanning. An important statistic to remember while reading this article is that the relative risk of melanoma for people who first use tanning beds before 35 years of age is 1.75; this translates into a 75% increased risk of developing melanoma.1
The causal environmental risk factor for development of both melanoma and nonmelanoma skin cancer (NMSC) is ultraviolet radiation, which is subdivided into UVA, UVB and UVC. In 2009, ultraviolet radiation was classified as a group 1 carcinogen (alongside asbestos, cigarettes and arsenic) by the International Agency for Research on Cancer (IARC), a World Health Organization (WHO) agency. This was due to the substantial amount of evidence linking ultraviolet radiation to skin cancer.2 Since the 1980s, tanning beds emit mostly UVA radiation and less than 5% UVB radiation; however, the FDA does not regulate these amounts.3 Studies have shown that both UVA and UVB radiation cause DNA damage and skin cancer. UVB induces DNA damage directly by the formation of cyclobutane pyrimidine dimers, while UVA induces DNA damage indirectly via generation of reactive oxygen species that cause oxidative DNA damage.4, 5 However, recent research has indicated that human skin exposed to UVA also produces cyclobutane pyrimidine dimers.6 Ultraviolet radiation also plays a role in melanoma development through immune modulation via inflammation and immunosuppression.4 Comparing the ultraviolet radiation of tanning beds to natural midday sun, studies have shown the ultraviolet intensity of tanning beds to be 10-15 times higher.1 In addition to these environmental factors, there are also various unmodifiable genetic factors that may contribute to the development of melanoma and other skin cancers.4
Statistics concerning new cases are alarming. The incidence of melanoma continues to increase rapidly in men and women of all age groups in the United States, with greater than 95% of cases occurring in non-Hispanic white men and women. Melanoma rates in men exceed those in women by 50% for incidence and more than 50% for mortality. The only exception to this pattern is the higher incidence of melanoma in women than in men aged 15 to 39 years.7 In the United States in 2010, estimates showed that 1 in 39 people will be diagnosed with melanoma during their lifetime, an increase from 1 in 600 in 1965 and 1 in 150 in 1985.8 It is the most lethal of the skin cancers and accounts for approximately 8,500 U.S. deaths annually.9 The National Cancer Institute’s Surveillance, Epidemiology and End Results registry revealed that the age-adjusted annual incidence of melanoma from 1973 to 2004 in young men aged 15-39 increased from 4.7 to 7.7 cases per 100,000 persons and in young women aged 15-39, from 5.5 to 13.9 cases per 100,000 persons.10 At this time, melanoma is the second most commonly diagnosed cancer in women 20 to 29 years old with 68,000 new cases occurring in the United States in 2010.8
Then why is it that the incidence rates in young women are increasing so much higher than those in young men? The increasing incidence of melanoma among women not surprisingly parallels the increased exposure to ultraviolet radiation, the primary environmental cause of melanoma and a major modifiable risk factor.4 Specifically, tanning bed usage is increasing among U.S. adults, especially young women, leaving us to speculate that this is the likely explanation accounting for this difference in melanoma incidence between young women and men. It is estimated that indoor tanning facilities are used approximately 1 million times per day in the United States. Thirty million Americans including minors use tanning beds each year per estimates from the indoor tanning industry.11 A recent study found that the number of American adults reporting use of indoor tanning facilities increased from as few as 1% to 27% during the period from 1988 to 2007.12 Therefore, this issue has become an important public health problem which needs intervention.