Association of Indoor Tanning Frequency With Risky Sun Protection Practices and Skin Cancer Screening

Key Points

Question  How is indoor tanning frequency associated with behaviors related to skin cancer prevention?

Findings  This cross-sectional study using data from the US 2015 National Health Interview Survey found that young adults who frequently tanned indoors were significantly more likely to never/rarely use protective clothing or shade compared with young adults who did not tan indoors. Similar findings were observed among women.

Meaning  In 2 groups with high indoor tanning prevalence (young adults and women), frequent indoor tanners often exhibited a concurrent tendency to practice poor sun protection, which may increase their risk of skin cancer beyond the risk associated with indoor tanning alone.

Importance  Indoor tanning is prevalent among young adults and women and is associated with increased risk of melanoma. Evidence suggests that indoor tanners may be more inclined to adopt poor photoprotective practices that further increase their risk of skin cancer; however, gaps in the literature exist in young adults and by indoor tanning frequency.

Objective  To examine the association between indoor tanning frequency and behaviors related to skin cancer prevention and to investigate whether these associations vary by age group or sex.

Design, Setting, and Participants  Cross-sectional population-based study of US 2015 National Health Interview Survey data including 10 262 non-Hispanic white adults aged 18 to 60 years without a history of skin cancer.

Main Outcomes and Measures  Rare/never use of sunscreen, protective clothing, shade; multiple sunburns within the past year; previous full-body skin examination.

Results  Of the 10 262 individuals in our study population (49% female; median age, 39 y), 787 (7.0%) reported having tanned indoors in the past year. Among individuals aged 18 to 34 years, frequent indoor tanners (≥10 times in the past year) were more likely to report never/rare use of protective clothing (adjusted prevalence ratio [aPR], 1.28; 95% CI, 1.10-1.49) and shade (aPR, 1.32; 95% CI, 1.03-1.70), compared with individuals who did not tan indoors. Among women aged 18 to 60 years, those who frequently tanned indoors were more likely to rarely/never use sunscreen (aPR, 1.34; 95% CI, 1.11-1.62), protective clothing (aPR, 1.27; 95% CI, 1.15-1.42), and shade (aPR, 1.54; 95% CI, 1.25-1.90) on a warm sunny day, as well as more likely to report multiple sunburns in the past year (aPR, 1.21; 95% CI, 1.00-1.45) compared with those who did not tan indoors. Individuals who tanned indoors in the past year were not significantly more likely to have undergone a previous full-body skin examination in any subpopulation examined.

Conclusions and Relevance  Individuals who tan indoors often exhibited a concurrent tendency to sunburn, avoid sun protection, and avoid skin cancer screening. Thus, the findings highlight that in addition to tanning bed avoidance, it is critical to emphasize sun protection and skin cancer screening in individuals who tan indoors.

Indoor tanning is associated with an increased risk of melanoma,¹ with higher risk among individuals initiating indoor tanning prior to age 35 years.² Indoor tanning is also associated with increased sun exposure,^3-5 which may increase the risk for skin cancer beyond the risk that is attributable to indoor tanning alone. Individuals who tan indoors may similarly be less likely to engage in primary and secondary skin cancer prevention behaviors. Yet, the reported results to date that examine the association between indoor tanning and sun protection vary by age, sex, and geographic location,^4-9 with little focus on the young adult population, despite the high prevalence of indoor tanning in this age group.¹⁰ Furthermore, studies evaluating the association between increasing frequency of indoor tanning and behaviors related to primary and secondary skin cancer prevention are limited. The objectives of the study were thus (1) to explore the association between indoor tanning frequency and behaviors related to primary and secondary skin cancer prevention and (2) to examine whether this association varied by age or sex.

The study was conducted using self-reported data from the 2015 National Health Interview Survey (NHIS) (N = 33 672; final adult response rate, 55.2%), which uses a multistage survey design to generate a representative sample of the US civilian noninstitutionalized population.¹¹ The analysis was limited to non-Hispanic whites (N = 20 855) because of the high prevalence of indoor tanning and high incidence of skin cancer in this subgroup relative to other subgroups.^10,12 Respondents with a history of skin cancer (N = 1076) were excluded to minimize bias from postcancer behavioral changes.¹³ The study population was further limited to participants aged 18 to 60 years (N = 12 952) because of the lower prevalence of indoor tanning in older persons.¹⁰ Individuals (N = 620) who responded that they “do not go out in the sun” to any of 7 questions defined herein (tanning ability, sun sensitivity, sunscreen, shade, wide-brimmed hat, long sleeves, long pants) were excluded for greater comparability of sun exposure profiles across categories of indoor tanning frequency, as other survey questions quantifying sun exposure were unavailable and as frequency of sunscreen, protective clothing, and shade use was not obtainable in these individuals. The study used deidentified data and was therefore exempt from review by the Johns Hopkins University Institutional Review Board.

Frequency of indoor tanning was defined by the NHIS as the number of times in the past 12 months that a survey respondent had used a sunlamp, sunbed, or tanning booth (not including spray-on tans). Responses were categorized as none (0 times), moderate (1-9 times), and frequent (≥10 times) indoor tanning with consideration for the frequency distribution and comparability with previous literature.¹⁰ Self-reported age, sex, region of the United States, family history of skin cancer, highest level of education, and body mass index (BMI) were reported. Tanning ability was characterized by the NHIS as the skin’s appearance after being out in the sun repeatedly, such as every day for 2 weeks, without sunscreen, a hat, or protective clothing. Sun sensitivity was characterized by the NHIS as the skin’s response to going out into the sun for 1 hour without photoprotection after several months of sun avoidance. Physical activity level was categorized using the sum of reported minutes of mild to moderate and vigorous activity per week.

Survey respondents were asked 5 questions regarding how often they (1) use sunscreen, (2) stay in the shade, (3) wear a hat that shades their face, ears, and neck, such as a hat with a wide brim all around, (4) wear a long-sleeved shirt, and (5) wear long pants or other clothing that reaches their ankles, when they go outside on a warm sunny day for more than 1 hour. For each of the 5 questions, we included responses of always, most of the time, sometimes, rarely, or never. For stable estimates, we combined responses of rare and never use. We defined rare/never use of protective clothing to be individuals who did not report at least sometimes using a wide-brimmed hat, long sleeves, or long pants for stable estimates and generalizability. Multiple sunburns indicated at least 2 sunburns reported within the past 12 months. Previous full-body skin examination was assessed by asking respondents, “Have you ever had all of your skin from head to toe checked for cancer either by a dermatologist or some other kind of doctor?”¹⁴

Bivariate associations between indoor tanning frequency and other covariates were assessed using the Rao-Scott χ² test for categorical variables and the global F test from linear regression analyses for continuous variables (BMI, age). Multivariable Poisson regression¹⁵ was performed in the context of the Taylor series (linearized) method for variance estimation¹¹ to estimate adjusted prevalence ratios (aPRs) for the outcome variables of interest using indoor tanning frequency as the main exposure variable. All regression analyses were adjusted for potential confounders that were a priori predictors of the primary outcomes^16,17 and significantly associated with the main exposure variable in bivariate analyses. Further adjustment for family history of skin cancer and physical activity level did not substantially affect point estimates in any models (data not shown); therefore, the more parsimonious models without these additional covariates were used. Estimates of association did not substantially differ when using only persons with a complete set of data compared with using multiple imputation for missing data by generating 20 imputed data sets using chained equations; thus, findings using the former method are presented (N = 10 262). The P_trend was computed using the Wald statistic treating the median frequency in each indoor tanning category as continuous. All analyses were performed (Stata, version 14.0) taking into account the complex survey design and population-based weights.¹¹

The final study population of 10 262 sun-exposed non-Hispanic white adults with no reported history of skin cancer represented approximately 30% of the 2015 US adult population, equating to an estimated 85 million individuals. Among all respondents in our study population (Table 1), 3.6% reported moderate indoor tanning (1-9 times in the past year; median of 3 times) and 3.4% reported frequent indoor tanning (≥10 times in the past year; median of 20 times), with a higher prevalence of frequent indoor tanning among women (5.8%). Differences in the distribution of age, sex, geographic region, sensitivity to sunburn, tanning ability, education, and BMI were observed according to indoor tanning frequency (Table 1).

In the overall study population, more frequent tanning bed use was associated with poor use of sunscreen, protective clothing, and shade and was associated with having sunburned multiple times in the past year (eTable in the Supplement). Among individuals aged 18 to 34 years (Table 2), those who frequently tanned indoors compared with those who did not tan indoors in the past year were more likely to report rarely/never wearing protective clothing (aPR, 1.28; 95% CI, 1.10-1.49) and rarely/never seeking shade (aPR, 1.32; 95% CI, 1.03-1.70) on a warm sunny day. Similar associations were observed among individuals aged 35 to 60 years. Additionally, among individuals aged 35 to 60 years, frequent indoor tanners were more likely to report rarely/never applying sunscreen (aPR, 1.29; 95% CI, 1.02-1.62) and moderate indoor tanners were more likely report multiple sunburns in the past year (aPR, 1.62; 95% CI, 1.24-2.10) compared with those who did not tan indoors.

Women who frequently tanned indoors compared with women who did not tan indoors were more likely to report rarely/never applying sunscreen (aPR, 1.34; 95% CI, 1.11-1.62), rarely/never wearing protective clothing (aPR, 1.27; 95% CI, 1.15-1.42), rarely/never seeking shade (aPR, 1.54; 95% CI, 1.25-1.90), and multiple sunburns in the past year (aPR, 1.21; 95% CI, 1.00-1.45) (Table 3). Among men, those who frequently tanned indoors were more likely to rarely/never seek shade compared with those who did not tan indoors (aPR, 1.45; 95% CI, 1.03-2.03). Men who moderately tanned indoors were more likely to rarely/never use protective clothing (aPR, 1.45; 95% CI, 1.15-1.83) and to report multiple sunburns in the past year (aPR, 1.55; 95% CI, 1.09-2.21) compared with men who did not tan indoors.

Using nationally representative data, our findings are generalizable to non-Hispanic white adults aged 18 to 60 years without previous skin cancer and reporting sun exposure. This study observed that individuals who frequently tanned indoors were more likely to report poor sun-protective practices on a warm sunny day and were more likely to report multiple sunburns in the past year, compared with individuals who did not tan indoors in the past year. Among individuals aged 18 to 34 years, frequent indoor tanners were more likely to report never/rare use of protective clothing and shade compared with individuals who did not tan indoors. Among women aged 18 to 60 years, those who frequently tanned indoors were more likely to rarely/never use sunscreen, protective clothing, and shade on a warm sunny day, as well as more likely to report multiple sunburns in the past year compared with those who did not tan indoors. Individuals who tanned indoors were not significantly more likely to have undergone a full-body skin examination compared with individuals who did not tan indoors, regardless of sex or age group.

This study adds to the literature examining the association between indoor tanning and behaviors related to primary and secondary skin cancer prevention^4-9 by contributing recent information in the US population and offering more detailed information on frequency of indoor tanning by sex and in different age groups. The finding among young adults aged 18 to 34 years that frequent indoor tanners were more likely to avoid certain sun-protective practices than individuals who did not tan indoors contributes to the limited literature in this age group, despite evidence to support that this age group exhibits higher prevalence of indoor tanning and stronger effects of indoor tanning on the risk of melanoma relative to older adults.^2,10 The overall association between frequent indoor tanning and poor sunscreen use complements other studies in the United States^4,7,9; however, the associations with protective clothing, shade, and sunburn have not been examined in this population. The observation that sun-protective behaviors worsened as the frequency of indoor tanning increased highlights that individuals in the United States who are at elevated risk for skin cancer due to frequent indoor tanning are more likely to further increase their risk by implementing poor sun protection. Whereas prior evidence suggests that a higher percentage of individuals who tan indoors seek skin cancer screening compared with individuals who do not tan indoors,¹⁷ our analysis using more recent data failed to observe a significant association, even when combining all individuals who tanned indoors in the past year regardless of frequency. Evidence suggests that the prevalence of indoor tanning use is strikingly higher in females vs males and in younger vs older adults.¹⁰ As increasing frequency of indoor tanning has been shown to increase the risk of skin cancer in a dose-dependent manner,² indoor tanning is a public health concern and may contribute to the increasing incidence of melanoma observed among young women.^18,19 This study observed that recent indoor tanning frequency was associated with poor use of sun protection in a dose-dependent manner among women.

Limitations of the study include the self-reported nature of the data that is subject to recall bias; the cross-sectional study design that prevented examination of the temporal direction of associations to make any causal inferences; the lack of information on self-administered skin cancer screening, which is an important form of early skin cancer detection; and information quantifying sun exposure, although individuals who denied sun exposure were excluded. Furthermore, the limited number of individuals reporting indoor tanning prevented the exploration of associations in smaller subpopulations and may have contributed to lack of significance observed in some subgroups.

Individuals who frequently tan indoors already have a worrisome risk factor profile for skin cancer, yet they continue to practice poor photoprotection along with increased sun exposure, increasing their risk for skin cancer beyond that associated with the use of indoor tanning alone. Yet, despite their heightened risk factor profile, individuals who frequently tan indoors are not significantly more likely to engage in skin cancer screening. These results demonstrate that many individuals who tan indoors may not acknowledge the long-term risks associated with increased UV exposure. Thus, these findings highlight the importance of not only emphasizing avoidance of indoor tanning in public health messages and physician communication, but also reiterating the need for sun protection and skin cancer screening in this population. Proper sun protection is critical in guarding against harmful UV irradiation associated with the development of skin cancers.^20-22 Regular skin examination plays an equally vital role in reducing skin cancer risks. Patients who received a full-body skin examination in the year prior to their melanoma diagnosis were significantly more likely to have thinner tumors,²³ which are associated with better prognosis and survival.^24,25 Thus, taking an active approach to sun protection and skin cancer screening in high-risk populations, such as indoor tanners, may reduce the morbidity and mortality associated with skin cancer.

Corresponding Author: Alexander H. Fischer, MPH, Department of Dermatology, Johns Hopkins University School of Medicine, 733 N Broadway, Edward D. Miller Research Bldg, Ste 137, Baltimore, MD 21205-2196 (afisch11@jhmi.edu).

Published Online: October 12, 2016. doi:10.1001/jamadermatol.2016.3754

Author Contributions: Mr Fischer had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Study concept and design: Fischer, Wang, Chien.

Acquisition, analysis, or interpretation of data: All authors.

Drafting of the manuscript: Fischer.

Critical revision of the manuscript for important intellectual content: All authors.

Statistical analysis: Fischer, Yenokyan, Chien.

Administrative, technical, or material support: Fischer, Wang, Kang, Chien.

Study supervision: Fischer, Wang, Chien.

Conflict of Interest Disclosures: None reported.

Funding/Support: This study was supported in part by the Johns Hopkins Institute for Clinical and Translational Research (ICTR), which is funded in part by grant TL1 TR001078 from the National Center for Advancing Translational Sciences (NCATS), a component of the National Institutes of Health (NIH), and NIH Roadmap for Medical Research. Funding for the statistical analysis was supported in part by the National Center for Research Resources and the NCATS of the NIH through grant 1UL1TR001079.

Role of the Funder/Sponsor: The funders had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.

Disclaimer: The contents of this publication are solely the responsibility of the authors and do not necessarily represent the official view of the Johns Hopkins ICTR, NCATS, or NIH.

Previous Presentation: A modified version of these findings was presented at the 2015 Society for Investigative Dermatology annual meeting; May 6-9, 2015; Atlanta, Georgia.