Introduction
Tanning bed use, also commonly known as indoor tanning, has been a topic of discussion in recent years in regards to level of risk and long-term effects, in particular skin damage and ultimately, malignancy. Though we have long known that ultraviolet radiation from outdoor tanning is a risk factor for development of melanoma and non-melanoma skin cancers, the link between tannings beds has been slower to develop. In 2009, the World Health Organization classified ultraviolet radiation–emitting tanning devices as Class I carcinogens based on evidence linking indoor tanning to increased risk of skin cancer1,2. Despite efforts by regulatory agencies such as state and national government to limit use in at-risk age groups, using age limit laws and need for parental consent, campaigns by tanning bed companies have persisted over the last decade, and often promote the health benefits of indoor tanning, such as increased vitamin D production. We know that skin is the most common site of cancer in the United States and its rising incidence in young adults warrants discussion and attention3.
The Data
Recent studies estimate the number of skin cancers that may be caused by indoor tanning each year – more than 170,000 cases of squamous and basal cell carcinomas in the U.S., and more than 3400 cases of melanoma in Europe4,5. Indoor tanning is the most common amongst young adults aged 18-25 and use decreases with age6. Tanners are more likely to be female, Caucasian, appearance-sensitive and have other unhealthy behaviors such as alcohol use, tobacco or drug use7,8. Tanning has been associated with self-esteem, and the increasing use of social media has perpetuated the perceived social norms of tanned skin9-13. Older data examining the association between skin cancer and tanning bed use often did not include this population, so cannot be extrapolated to this group. More recent studies have worked to clarify the relationship between age at first use and long-term sequela. Age at first use less than 20 years has been associated with the highest risk for both basal and squamous cell cancers14. Melanoma is one of the most commonly diagnosed cancers among adolescents and young adults in the U.S, and is the most deadly skin cancer15. Initial tanning bed use at age 35 years or less increases the risk of melanoma by 60%–80% or more4,16.
From a molecular perspective, ultraviolet exposure in both the UVA and UVB ranges has been shown to induce DNA damage in the skin, initiating carcinogenesis17,18. This process has been found to occur via mutations in the genome as well as by loss of p53 tumor suppressor function19,20. Though this relationship is applicable to both indoor and outdoor tanning, we will focus on indoor tanning. Studies focused at indoor tanning have increasingly shown a significant association between ever-use of indoor tanning and the risk of development of basal and squamous cell cancers, as well as melanoma3,14,21-23. In particular, this association is strongest in those that began using indoor tanning in young adulthood3,23. A landmark study performed in 2007 by the International Agency for Research on Cancer affirmed the association between indoor tanning and melanoma24. This meta-analysis of 19 studies across 24 years and including 7355 cases of melanoma, showed a relative risk of 1.15 of developing melanoma with ever-use of indoor tanning. Further, first use prior to age 35 demonstrated relative risk of 1.75 to develop melanoma. Compiled data now indicates a clear association between indoor tanning and skin cancer.
Ultraviolet exposure stimulates the conversion of 7-dehydrocholesterol to pre-vitamin D which is processed into active vitamin D in the liver and kidney. Promotors of indoor tanning list the health benefits related to vitamin D and sometimes perpetuate an unproven assertion that vitamin D is associated with protection AGAINST cancer3,25. Further, those most likely to use tanning beds (Caucasians) are those least likely to be vitamin D deficient26,27. Though Vitamin D does hold valuable health benefits particularly in the form of skeletal and cardiovascular health, the long-term risk for development of cutaneous malignancy and need for proper screening cannot be understated. Given the increasing influence of social media in the lives of our youth, appropriate early primary care education is critical. Further education regarding other sources of vitamin D acquisition such as supplements and diet is necessary.
Important to consider also are the economic and resource impacts of skin cancer on our health care system. The treatment of melanoma and non-melanoma skin cancer costs an estimated $1.7 billion each year. Costs due to lost productivity are estimated to be $3.8 billion28. Expense of provider work-hours in education, screening, and treatment of malignant skin lesions related to avoidable causes such as tanning beds should not be underestimated. In a US population living longer and more apt to develop cutaneous malignancies with time, reduction of avoidable lesions is critical to resource preservation.
Conclusion
Indoor tanning, most commonly in the form of tanning bed use, as with outdoor tanning, has unequivocally been linked to increased risk of skin cancer, including squamous cell, basal cell, and melanoma. Indoor tanning occurs most commonly in the young adult population, and a wealth of data now suggests that earlier age at first use increases the likelihood of developing malignancy. Tanning industry and social media influences threaten the safety of this population with misinformation regarding the health benefits of tanning, in particular to vitamin D levels. Early education is imperative to public health and health care resource protection long-term.
References
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