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Keywords:

  • artificial UV;
  • BCC;
  • cutaneous malignancy;
  • melanoma;
  • nail lamp;
  • non-melanoma skin cancer;
  • NMSC;
  • SCC;
  • solarium;
  • sunlamps;
  • tanning bed

Abstract

  1. Top of page
  2. Abstract
  3. Method
  4. The Changing Incidence of Cutaneous Malignancy
  5. Compliance with Legislation
  6. The Role of UVR in Cutaneous Carcinogenesis
  7. Differences in Solar and Artificially Derived UVR and the Implications for Cutaneous Carcinogenesis
  8. Studies that Support a Positive Association Between Tanning Beds and MM
  9. Evidence Against Commonly Promoted ‘Benefits’ of Indoor Tanning
  10. Limitations of the Current Evidence
  11. Future Studies
  12. Conclusion
  13. References

Malignant melanoma (MM) and non-melanoma skin cancer (NMSC) are increasingly common and both can be fatal. In 2009 the World Health Organization (WHO) classified the whole ultraviolet spectrum and tanning beds as carcinogenic to humans, placing them in the same category as asbestos and tobacco. Despite this, the trend for indoor tanning continues. A growing body of evidence has now associated indoor tanning with an increased risk of MM and NMSC. As a result, there has been an upsurge in regulations in the tanning industry ranging from age restrictions to complete bans on commercial tanning. This article examines the evidence and strengthens the case for a complete ban of a recognised modifiable risk factor for cutaneous malignancy.


Abbreviations
BCC

basal cell carcinoma

IARC

International Agency for Research on Cancer

MM

malignant melanoma

NMSC

non-melanoma skin cancer

SCC

squamous cell carcinoma

UVR

UV radiation

WHO

World Health Organization

Method

  1. Top of page
  2. Abstract
  3. Method
  4. The Changing Incidence of Cutaneous Malignancy
  5. Compliance with Legislation
  6. The Role of UVR in Cutaneous Carcinogenesis
  7. Differences in Solar and Artificially Derived UVR and the Implications for Cutaneous Carcinogenesis
  8. Studies that Support a Positive Association Between Tanning Beds and MM
  9. Evidence Against Commonly Promoted ‘Benefits’ of Indoor Tanning
  10. Limitations of the Current Evidence
  11. Future Studies
  12. Conclusion
  13. References

A narrative review of the literature was conducted on PubMed (1966 to the present) and Embase (1974 to the present) using the following keywords: tanning beds, sunlamps, solarium, melanoma, cutaneous malignancy, non-melanoma skin cancer, NMSC, BCC and SCC. A Google search was also carried out using the same terms.

The Changing Incidence of Cutaneous Malignancy

  1. Top of page
  2. Abstract
  3. Method
  4. The Changing Incidence of Cutaneous Malignancy
  5. Compliance with Legislation
  6. The Role of UVR in Cutaneous Carcinogenesis
  7. Differences in Solar and Artificially Derived UVR and the Implications for Cutaneous Carcinogenesis
  8. Studies that Support a Positive Association Between Tanning Beds and MM
  9. Evidence Against Commonly Promoted ‘Benefits’ of Indoor Tanning
  10. Limitations of the Current Evidence
  11. Future Studies
  12. Conclusion
  13. References

The worldwide incidence of both malignant melanomas (MM) and non-melanoma skin cancer (NMSC) is increasing. In total 132 000 cases of malignant MM and over two million cases of NMSC occur worldwide each year. One in every three cancers diagnosed worldwide is a skin cancer.[1] One person dies every hour from MM in the USA.[2]

Australia has the highest incidence of skin cancer in the world. Two-thirds of Australians will be diagnosed with skin cancer before the age of 70, with over 2000 Australians dying from skin cancer each year.[3] MM is the third most common cancer in Australian men and women, and the most common cancer in those aged 15–44 years. In 2007, 1279 deaths were attributed to invasive MM and NMSC accounted for 80% of all cancers diagnosed in Australia.[4] Both MM and NMSC place an increasing and significant burden on health-care services.[4] In Australia the total financial cost of NMSC (diagnosis, pathology and treatment) was estimated to be $511 million in 2010, with a projected increase to $703 million (excluding inflation) by 2015.[5]

Current legislation

In 2009 the World Health Organization (WHO) listed ultraviolet radiation and tanning beds as a group 1 carcinogen.[6] In the USA the Food and Drug Administration currently classifies tanning beds as class 1 devices, safe to use, subject to the least regulatory control and in the same category as examination gloves and elastic bandages. They have proposed to upgrade this to class II; however at the time of writing this has not been confirmed.

The risks associated with indoor tanning have been recognised by many countries, with varying degrees of regulation. The most stringent is the complete ban on the use and sale of tanning devices implemented in Brazil in 2011. In Australia state governments have introduced regulations for their use with regard to the user's age, skin type and their informed consent.[7] Last year New South Wales was the first state to announce a complete ban on commercial tanning from 2014, with a buy-back scheme to prevent the reuse of equipment and financial penalties for breaches of the legislation. Subsequently South Australia, Victoria, Australian Capital Territory, Tasmania and Queensland have announced bans from 2014–2015. The other Australian states and New Zealand are currently considering legislation but refer to the voluntary Australian Standard.[8] In 2013 Auckland announced a by-law requiring all solaria to be licensed and banning their use by individuals under the age of 18. At the time of publication no complete bans exist in New Zealand. Globally, 22 countries and 18 UA states have legislation prohibiting those aged 18 or younger from using commercial tanning beds.[9]

Compliance with Legislation

  1. Top of page
  2. Abstract
  3. Method
  4. The Changing Incidence of Cutaneous Malignancy
  5. Compliance with Legislation
  6. The Role of UVR in Cutaneous Carcinogenesis
  7. Differences in Solar and Artificially Derived UVR and the Implications for Cutaneous Carcinogenesis
  8. Studies that Support a Positive Association Between Tanning Beds and MM
  9. Evidence Against Commonly Promoted ‘Benefits’ of Indoor Tanning
  10. Limitations of the Current Evidence
  11. Future Studies
  12. Conclusion
  13. References

Tanning salons remain largely unregulated. Research has shown there is widespread non-compliance with regulations with regard to posting appropriate warning signs, obtaining users' informed consent, restrictions of users with respect to their age and skin-type, restrictions of the frequency of sessions, the intensity of UV radiation (UVR)used and the failure of operators to inform their patrons of the risks.[10, 11] Levine and colleagues note that the guidelines may inadvertently promote tanning if tanning salons advertise that they are following scientific guidelines for safe tanning.[12] The requirement of parental consent in the USA was found to be ineffective, as parents often also used tanning beds.[13, 14] Behavioural research has shown that improving knowledge of the risks of UVR is insufficient to change behaviour in adolescents.[15, 16]

The Role of UVR in Cutaneous Carcinogenesis

  1. Top of page
  2. Abstract
  3. Method
  4. The Changing Incidence of Cutaneous Malignancy
  5. Compliance with Legislation
  6. The Role of UVR in Cutaneous Carcinogenesis
  7. Differences in Solar and Artificially Derived UVR and the Implications for Cutaneous Carcinogenesis
  8. Studies that Support a Positive Association Between Tanning Beds and MM
  9. Evidence Against Commonly Promoted ‘Benefits’ of Indoor Tanning
  10. Limitations of the Current Evidence
  11. Future Studies
  12. Conclusion
  13. References

The aetiology of MM and NMSC is accepted as being multifactorial. Risk factors for both can be divided into those that are host-related (phenotypic, genetic and immunological factors) and environment-related (including natural and artificial UVR) and the interactions between them.[17] The former are currently unmodifiable, the latter can be controlled.

The mechanisms of cutaneous carcinogenesis from both UVA and UVB exposure are now well established and include direct DNA damage and mutations as well as local immunosuppression.[18-28]

Differences in Solar and Artificially Derived UVR and the Implications for Cutaneous Carcinogenesis

  1. Top of page
  2. Abstract
  3. Method
  4. The Changing Incidence of Cutaneous Malignancy
  5. Compliance with Legislation
  6. The Role of UVR in Cutaneous Carcinogenesis
  7. Differences in Solar and Artificially Derived UVR and the Implications for Cutaneous Carcinogenesis
  8. Studies that Support a Positive Association Between Tanning Beds and MM
  9. Evidence Against Commonly Promoted ‘Benefits’ of Indoor Tanning
  10. Limitations of the Current Evidence
  11. Future Studies
  12. Conclusion
  13. References

Solar UVR

Solar UVR is the major risk factor for MM and NMSC. Solar UVR consists of UVA (wavelength 320–400 nm), UVB (290–320 nm), UVC (100–290 nm), visible light (400–700 nm) and infrared radiation (> 700 nm). UVC and most of UVB is absorbed by the atmosphere and ozone layer. Approximately 95% of UVA and 10% of UVB reaches the earth.[28] An individual's UV exposure is influenced by factors including latitude, altitude, cloud cover, time of day and atmospheric pollution.

Artificial UVR

Tanning beds UVR output varies greatly and differs considerably from solar UVR in terms of the type of UVR (UVA predominates over UVB), the ratio of UVA to UVB and intensity. Pre-1980 arc mercury sunlamps used in the home used to be the predominant source of artificial UVR available to the public. These lamps emitted UVB and UVC wavelengths. The popularisation of tanning beds in the 1980s saw the output change to be predominantly 99% UVA and 1% UVB[29] and tanning salons offered more tanning with less burning. During the 1990s high speed, high pressure and high-intensity devices were introduced and promised a deeper tan. Most recently the percentage of UVB emitted by tanning beds has been increased to as much as 5% of the total, with UVA accounting for the remainder.[12, 30, 31]

In the 1980s, as most cutaneous damage was attributed to UVB, the tanning industry marketed predominantly UVA sunlamps as safe. However, in 1993 Setlow and colleagues published evidence that suggested that 90–95% of MM may be attributed to UVA wavelengths (> 320 nm).[32] By 2005 it was stated that there remains no convincing body of evidence that UVB is more or less strongly associated with skin cancer development than UVA.[33] Additionally, there was no good evidence to suggest that solar UVR is more carcinogenic than artificial UVR. Research has shown that exposure to tanning-bed UVA causes DNA damage similar to that resulting from solar exposure.[34]

One study of 62 tanning beds in a US state found that the UVA output of tanning beds was fourfold more than noon sunlight during the summer and that the UVB output was over double the amount in midday sun.[22] Others have noted that powerful tanning devices may produce UVR that is 10–15-fold stronger than the midday sun in the Mediterranean.[14] The annual UVA doses of frequent indoor tanners may be 1.2–4-fold that received from the sun, in addition to sun exposure.[35-37]

The tanning industry

Across the western world the tanning industry is big business: in the US alone it employs over 160 000 people and profits are over US $5 billion per year.[38] The number of solaria and their commercial profile increased from 1996–2006.[4] One US study reported that tanning salons were more common than either Starbucks or McDonald's.[38] Another study reported that tanning salon use in those aged 25 and under has increased over recent years, from 8% in 1996 to 26% in 2003.[36] Parallel to this, the incidence of both MM and NMSC has increased dramatically, especially among young women.[39, 40]

Indoor tanning is advertised as a safe alternative to the sun, promising an improved cosmetic appearance, psychological well-being and vitamin D biosynthesis. A tan continues to be seen as socially desirable and attractive, especially among the adolescent population. The media promotes images that associate tanned skin with health and fitness. Several studies have revealed that public perceptions of artificial tanning include the view that is safe and healthy, and that it is a way to prepare the skin before it is exposed on vacation and helps to improve one's appearance.[41, 42]

According to the 2010 National Health interview survey (USA), indoor tanners tended to be young, non-Hispanic white women. A recent UK study found that 57% of women reported using tanning beds as compared to 38% of men.[43] An Australian study found that 14% of women aged 25–44 and 7% of girls aged 15–17 use tanning beds.[44] The 2011 US youth risk behaviour surveillance system found that 13% of all high school students, 21% of high school girls, 32% of girls in 12th grade and 29% of white high school girls used indoor tanning. An estimated 6% of children aged 11–17 have used a tanning bed in the UK, which equates to approximately 250 000 children.[45] Similar figures for tanning in children and adolescents have been reported in other countries

A recent study in the UK reported that most tanning beds were used in private homes.[43] Home tanning beds are of particular concern, as the addictive nature of tanning is well documented and regulation of tanning bed use is impossible. The large percentage of tanning salons in gyms and spas only reinforces the false association of tanning with health and well-being. A recent study of children aged 11–17 years in UK cities found that almost a quarter had used a tanning bed at the home of a friend or relative and the same number admitted to using tanning beds unsupervised in a tanning or beauty salon or gym.[45]

Studies that Support a Positive Association Between Tanning Beds and MM

  1. Top of page
  2. Abstract
  3. Method
  4. The Changing Incidence of Cutaneous Malignancy
  5. Compliance with Legislation
  6. The Role of UVR in Cutaneous Carcinogenesis
  7. Differences in Solar and Artificially Derived UVR and the Implications for Cutaneous Carcinogenesis
  8. Studies that Support a Positive Association Between Tanning Beds and MM
  9. Evidence Against Commonly Promoted ‘Benefits’ of Indoor Tanning
  10. Limitations of the Current Evidence
  11. Future Studies
  12. Conclusion
  13. References

Increased incidence

The increased incidence of MM and NMSC in young women has been associated with the more frequent use of indoor tanning beds in this age group.[46] An Icelandic study demonstrated an increase in the incidence of MM from 1990 to 2000 which appeared to correspond with an increase in tanning salons in Reykjavik from three in 1979 to 207 salons in 1988.[47] A decline in the incidence of MM was noted after a reduction in tanning beds after 2001. Despite its ecological nature, this study demonstrates a trend that has since been substantiated by more robust research. The largest systematic review published to date evaluated prevalence data from 18 countries in 2008 and attributed a potential 3438 cases of MM (2341 of which were in women) to tanning bed use.[14]

Increased dosage and intermittent exposure to UVR

Artificial sources of UVR provide potentially larger doses than solar UVR. High doses of UVA from tanning beds in conjunction with high outdoor solar exposure may have an important role in the increased incidence of MM in young women.[46] Tanning beds may increase risk by simply increasing lifetime exposure to UVR. Intermittent exposure to UVR has been linked to an increased risk of MM.[48, 49]

Anatomical site of cutaneous malignancy

Tanning bed usage increases whole body exposure to UVR and increases the exposure of areas usually protected by clothing. A large case–control study found that body sites not commonly exposed to sunlight were common sites for primary MM in those who frequented indoor tanning beds.[50] The rise in truncal MM and BCC could be attributed in part to the increased use of indoor tanning.[40]

Ever use of tanning beds

A 2005 meta-analysis of 10 studies showed a significant risk of ever usage (even once) of tanning beds and the subsequent development of MM.[33] A nested case–control study of 200 nurses with MM and 804 controls demonstrated that sunlamp usage or tanning salon attendance was a risk factor for MM after adjusting for potential confounding variables (ever vs never usage, OR 2.06, 95% CI 1.30–3.26).[51]

A systematic review in 2007 found that ever use of tanning beds was positively associated with MM (summary relative risk, 1.15; 95% CI, 1.00–1.31).[6] Ever use of tanning beds was also shown to increase MM risk, especially in those younger than 45 years or with tanning sessions lasting longer than 20 min.[6] The largest systematic review and meta-analysis to date found that ever use of indoor tanning devices increased the risk of cutaneous MM by 20%.[14]

Dose response

A large systematic review and meta-analysis published in July 2012 reported the existence of a dose response relation between tanning bed use and MM risk.[14] An analysis of cohort and population-based studies revealed a 1.8% (95% confidence interval 0–3.8%) increase in MM risk for each additional tanning bed session per year.[14] These findings were in contrast to the systematic review and meta-analysis conducted by the International Agency for Research on Cancer (IARC) in 2006, which found no consistent evidence of a dose response relationship between tanning bed use and MM.[52] However, at the time of the 2006 study there were insufficient studies to conduct a formal meta-regression analysis.

In the interim, several studies supported a dose response relationship including a 2007 survey of 1518 dermatology patients that found that tanning sessions lasting longer than 20 min increased the risk of MM.[53] A prospective study of 106 379 Scandinavian women in 2003 demonstrated that the use of a tanning bed more than once per month significantly contributed towards the risk of developing MM.[54] A large US case–control study in 1991–1992 found that an individual's risk of MM increased with the typical session time and frequency of sessions. They estimated that typical 5 min sessions would increase the risk of MM by 19% for frequent users (> 10 sessions) and by 3% for occasional users (1–9 sessions).[50]

Age at first exposure to tanning beds

A substantial body of evidence suggests that childhood and teenage exposure to UVR is associated with an increased risk of MM, although the mechanism remains unclear. Other researchers have found that young age at the initiation of indoor tanning increased cumulative exposure rather than increasing age–group-specific susceptibility among adolescents.[55]

There is evidence that both sunburn in early life and freckling as a child are particularly associated with a risk of cutaneous malignancy.[56] Studies of Australian migrants have contributed to the hypothesis that significant sun exposure during childhood may be important in the development of MM.[57]

The IARC published a meta-analysis demonstrating that those whose first exposure to tanning beds was before they attained 35 years of age were at significantly increased risk of MM (relative risk, 1.75; 95% CI, 1.35–2.26).[6] In a large survey, ever use of tanning beds in those younger than 45 years was also shown to increase MM risk.[53]

In 2009 the WHO reported that the risk of MM is increased by 75% in those under the age of 30 using tanning beds.[6] In 2011 part of the Australian melanoma family study, a multi-centre, population-based, case–control family study investigated 604 cases of MM diagnosed between the ages 18 and 39 years and 479 controls. They found that tanning bed use is associated with an increased risk of early-onset MM, with the risk increasing with greater use and earlier age at first use and for earlier onset disease (particularly MM diagnosed between the ages of 18–29 years).[58] A systematic review and meta-analysis of 27 observational studies of patients over 30 years of age with MM found that the risk of MM was doubled in those who had used tanning beds prior to the age of 35 years.[14]

Studies that support the positive association between tanning beds and NMSC

Similar to MM, the incidence of NMSC has increased dramatically over the last few decades. A recent UK study found that BCC diagnoses in those under 30 years of age increased by 145% between 1981 and 2006.[59] Researchers have suggested that the rising incidence of truncal BCC diagnoses in women under 40 year of age, similar to the rise in truncal MM, could be attributed to tanning bed use. The use of indoor tanning beds is most popular among young women and the trunk is more frequently covered up in routine sun exposure.[40, 60] There is substantial evidence that intermittent sun exposure is the main cause of BCC,[61] whereas SCC is related to cumulative, chronic sun exposure.[14] As the use of tanning beds occurs intermittently and is likely to be associated with a higher cumulative UVR exposure, tanning beds may well contribute towards the increased risk of both BCC and SCC.

In October 2012 a systematic review and meta-analysis that examined 12 studies with a total of 9328 cases of NMSC concluded that indoor tanning increases the risk of NMSC. Indoor tanning exposure (ever exposure) increased the risk of developing SCC by 67% and BCC by 29%.[62] Furthermore, exposure to indoor tanning under the age of 25 years was associated with an increased risk of BCC and a non-significant increased risk for SCC. The authors conclude that this suggests ‘a critical period for exposure during early life and a potential dose–response effect’ (p. 3).

These findings were in contrast to a previous meta-analysis that indicated that indoor tanning was a potential risk factor for NMSC[35] but due to inadequate sample sizes and available data no firm and consistent conclusions were drawn.

The counterarguments for an association between tanning beds and cutaneous malignancy

The tanning industry argues that the increased incidence of both MM and NMSC is due to increased education and the early detection of skin cancers at all ages rather than a direct result of increased usage of tanning beds. The issue of whether MM and NMSC in tanning bed users is due to tanning bed use or increased exposure to solar UVR in those users remains contentious. Several studies have found that individuals who use tanning beds also more frequently sunbathe outside,[63] making it difficult to attribute causality. An increasing number of studies have adjusted for sun exposure[43, 55, 64] and infer that the relative risks quoted are unlikely to be due to more natural sun exposure by tanning bed users.[14]

Evidence Against Commonly Promoted ‘Benefits’ of Indoor Tanning

  1. Top of page
  2. Abstract
  3. Method
  4. The Changing Incidence of Cutaneous Malignancy
  5. Compliance with Legislation
  6. The Role of UVR in Cutaneous Carcinogenesis
  7. Differences in Solar and Artificially Derived UVR and the Implications for Cutaneous Carcinogenesis
  8. Studies that Support a Positive Association Between Tanning Beds and MM
  9. Evidence Against Commonly Promoted ‘Benefits’ of Indoor Tanning
  10. Limitations of the Current Evidence
  11. Future Studies
  12. Conclusion
  13. References

‘The healthy tan’

Lim and colleagues have reported that tanning is a stress response of the skin, as the DNA damage intermediate for tanning is identical to the intermediate that causes cancer.[65, 66] Furthermore, the IARC have reported that exposure to both UVA and UVB light can weaken the immune system and increase the vulnerability of an individual to cancer and other pathologies.[52]

The ‘protective effect’ of indoor tanning

Many indoor tanners believe that tanning bed use, especially pre-vacation, may offer protection against burning in sunlight. The evidence does not support a protective effect of the use of tanning beds against damage to the skin from subsequent sun exposure.[6] Indeed, research indicates that a tanning bed tan confers minimal, if any, protection against sunburn and skin damage.[46, 55] UVB affords only minimal sun protection (factor 2) against subsequent skin damage.[67] UVA does not increase photo-protection or melanin production.[19] Several studies have reported that repeated sub-erythemal dose exposure does not provide any protection against DNA damage.[65, 67, 68]

The vitamin D benefit

There is some evidence to suggest that adequate serum 25-hydroxyvitamin D levels may be protective against certain types of cancer.[69] The tanning industry have exploited this evidence to promote indoor tanning as a safe source of vitamin D and their adverts claim that artificial UV exposure reduces the risk of cancer by increasing vitamin D levels.[70, 71]

Some recent studies have suggested there are protective effects of mild to moderate UV exposure against cancer.[72] However, it is UVB, not UVA, that provides the 300 nm wavelength of UVR that is required for pre-vitamin D synthesis in the skin. Research has shown that tanning bed UVR is excessive for vitamin D production.[12] A single session on a tanning bed provides 4.5–7-fold the amount of UVB required for vitamin D synthesis.[12] Indeed, extended tanning is reportedly counterproductive, as at 1 minimal erythema dose UVR-induced vitamin D production and destruction reach equilibrium.[12] In vitro and in vivo studies have suggested the importance of vitamin D in inhibiting carcinogenesis, in particular the effects of reduced cell proliferation, increased differentiation and reduced angiogenesis but further research in human models is required to establish a causal link.[73]

Diet and oral supplementation can provide a safer source of vitamin D and provide any protective effect offered against other cancers without the risks associated with tanning beds. Furthermore, oral vitamin D supplementation is widely available, affordable and safe and can offer a more accurate method of correcting any deficiency.[28]

Lack of sunburn with indoor tanning

The tanning industry argues that cancer risk from both indoor and outdoor tanning relates to burning rather than from total UV exposure. They claim that an absence of sunburn implies that no damage has occurred. However, there is considerable evidence that burns are common in indoor tanners and that such burns confer a increased risk of MM similar to that seen in outdoor burns.[74]

UV lamps in the nail industry

Recent reports in the media and scientific literature have highlighted the potential risks of UV lamps used to cure and dry nail polish in the nail industry. In the USA over 87% of nail salons were reported to be using UV lamps for this purpose, with such manicures rapidly gaining popularity. Patrons attend 1–4 times per month for such services. A recent US study found that 250 years of weekly exposure to these nail lamps would be required to reach the same UV dose as that found in one course of narrowband UVB treatment (15–30 treatments over 5–10 weeks). The authors concluded that exposure to UV nail lamps does not produce a significantly increased risk of developing skin cancer.[75]

Prior to this study, one case report series of two patients with a history of UV nail lamp exposure and dorsal hand SCC had concluded that this was a risk factor for the development of SCC.[76] Despite criticism for its anecdotal nature and spectral irradiance calculations[75] it prompted fears for the safety of such devices. Subsequently Diffey and colleagues used a mathematical model to combine age and UV exposure to compare the risk of developing SCC due to typical sun exposure to the risk induced by exposure to UVA nail lamps. They found that the risk of developing an SCC from UVA nail lamp exposure was very low and could be reduced to almost nothing by wearing fingerless gloves when the hands are being exposed.[77]

There remains a paucity of evidence in this area and further research is required to clarify the risk.

Limitations of the Current Evidence

  1. Top of page
  2. Abstract
  3. Method
  4. The Changing Incidence of Cutaneous Malignancy
  5. Compliance with Legislation
  6. The Role of UVR in Cutaneous Carcinogenesis
  7. Differences in Solar and Artificially Derived UVR and the Implications for Cutaneous Carcinogenesis
  8. Studies that Support a Positive Association Between Tanning Beds and MM
  9. Evidence Against Commonly Promoted ‘Benefits’ of Indoor Tanning
  10. Limitations of the Current Evidence
  11. Future Studies
  12. Conclusion
  13. References

There are many difficulties in evaluating the risk of tanning beds. The first is the variation in usage patterns over time: earlier studies may have underestimated the risk associated with indoor tanning, as it has since grown in popularity.[14]

There has been a change in spectral output over time, which before 1980 used predominately UVB and UVC and now predominately uses a UVA output with an increasing percentage of UVB. This may influence results, as not all subjects may have had comparable source exposures.

Dosage variation between tanning beds and salons has been noted, which is likely to be due to the failure of most tanning salons to calibrate their equipment to measure the output.[78] The compliance of tanning salons with recommended spectral output has been reported to vary.[79]

In earlier studies, small sample sizes and a lack of inclusion of those exposed to more modern high-dose tanning beds may have underestimated the risks involved in using tanning beds. It can be difficult to isolate the damage caused by artificial UVR versus solar UVR in individuals who use tanning beds and also sunbathe outdoors. The results may also be confounded by the skin type. However, with an increasing number of studies controlling for these two main potential confounders and others, it appears unlikely that this could nullify the significant results found in the large systematic reviews and meta-analyses published in 2012.

Most studies are observational and retrospective. Prospective study designs are thought to reduce the risk of recall bias but few currently exist in this area. Epidemiological study limitations including recall bias tend to bias results to the null, that is, no risk[78] Veierod specifically assessed the reproducibility of recall and found most participants had given reliable answers.[80] However, an interesting study by De Vries and colleagues[81] found that public awareness regarding tanning bed use as a risk factor for MM most likely resulted in underreporting both sun and tanning bed exposure in case–control studies. Furthermore, they suggest that selective participation in such studies may also influence the accurate evaluation of risk.

In recent studies the risks may have been underestimated due to insufficient lag times between first exposure or regular exposure and the diagnosis of malignancy. This may suggest that the true impact of tanning beds on the incidence of MM will be revealed over time. Estimates for this time lag have included 10[33] and 20[34] years from first exposure to tanning beds.

Future Studies

  1. Top of page
  2. Abstract
  3. Method
  4. The Changing Incidence of Cutaneous Malignancy
  5. Compliance with Legislation
  6. The Role of UVR in Cutaneous Carcinogenesis
  7. Differences in Solar and Artificially Derived UVR and the Implications for Cutaneous Carcinogenesis
  8. Studies that Support a Positive Association Between Tanning Beds and MM
  9. Evidence Against Commonly Promoted ‘Benefits’ of Indoor Tanning
  10. Limitations of the Current Evidence
  11. Future Studies
  12. Conclusion
  13. References

We believe there is already sufficient evidence to endorse a complete ban on all indoor tanning. If further studies are required, prospective cohort studies with large sample sizes are the gold standard and would further define if, when and why individuals develop cutaneous malignancies. Additional genetic studies focusing on susceptibility may help to further identify those at increased risk. All confounders, including host and environmental factors, must be taken into account in an effort to accurately attribute causality. The accurate measurement of the timing of exposure, spectral irradiance and dosage of artificial UVR used remains critical.[78] In addition, further monitoring of the use of artificial UV in nail salons is required to both qualify and quantify the risks involved.

Conclusion

  1. Top of page
  2. Abstract
  3. Method
  4. The Changing Incidence of Cutaneous Malignancy
  5. Compliance with Legislation
  6. The Role of UVR in Cutaneous Carcinogenesis
  7. Differences in Solar and Artificially Derived UVR and the Implications for Cutaneous Carcinogenesis
  8. Studies that Support a Positive Association Between Tanning Beds and MM
  9. Evidence Against Commonly Promoted ‘Benefits’ of Indoor Tanning
  10. Limitations of the Current Evidence
  11. Future Studies
  12. Conclusion
  13. References

The robust systematic reviews and meta-analyses published in 2012 have concluded that indoor tanning is associated with an increased risk of both MM and NMSC.[14, 62] UVR from artificial sources remains a major modifiable risk factor for the development of cutaneous malignancy. The research to date supports a complete ban of indoor tanning as it has shown that less stringent regulations are ineffective due to the lack of adherence to them[82] and enforcement of them.[11, 65] Australia and New Zealand are in a powerful position to lead the developed world by imposing a complete ban on indoor tanning. It is imperative to act on this evidence to reduce the risk of further avoidable morbidity and mortality.

References

  1. Top of page
  2. Abstract
  3. Method
  4. The Changing Incidence of Cutaneous Malignancy
  5. Compliance with Legislation
  6. The Role of UVR in Cutaneous Carcinogenesis
  7. Differences in Solar and Artificially Derived UVR and the Implications for Cutaneous Carcinogenesis
  8. Studies that Support a Positive Association Between Tanning Beds and MM
  9. Evidence Against Commonly Promoted ‘Benefits’ of Indoor Tanning
  10. Limitations of the Current Evidence
  11. Future Studies
  12. Conclusion
  13. References