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Abstract

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Acknowledgment
  8. References

Background  Epidemiologic studies have associated tanning bed exposure and cutaneous melanoma. The relationship between the extent of tanning bed exposure and the risk of melanoma has not been elucidated in detail.

Methods  Surveys assessing the extent of tanning bed exposure and the history of skin cancer, including malignant melanoma, were collected from academic dermatology clinic patients (n = 1518). Of these, 551 (36.3%) completed all components of the survey. The available medical records, including pathology reports (n = 501; 33%), were reviewed to confirm cases of skin cancer. Data on potential confounding factors, including indoor vs. outdoor occupation and leisure activities, Fitzpatrick skin type, history of blistering sunburn, use of sunscreen and sun protective clothing, history of phototherapy, and level of education, were assessed and compared.

Results  Of the patients surveyed, 487 (32.1%) reported tanning bed exposure. Women aged 45 years or younger accounted for about 60% of all tanning bed users. Seventy-nine cases of malignant melanoma were reported, 22 in women aged 45 years or younger. In the entire cohort, the “ever-use” of tanning beds was found to be a significant risk factor for the development of melanoma [P < 0.05; odds ratio (OR), 1.64; 95% confidence interval (95% CI), 1.01–2.67]. The risk was greater in women aged 45 years or younger (P < 0.05; OR, 3.22; 95% CI, 1.01–11.46). Patients with a history of melanoma were significantly more likely to report tanning bed sessions exceeding 20 min (P < 0.01; OR, 3.18; 95% CI, 1.48–6.82); this association was even stronger for women aged 45 years or younger (OR, 4.12; 95% CI, 1.41–12.02).

Limitations  The study was subject to recall bias, included only patients at a midwestern academic practice, and had a relatively low response rate.

Conclusion  Exposure to tanning beds increases the risk of malignant melanoma, especially in women aged 45 years or younger. These findings reinforce the hazards of tanning bed exposure.


Introduction

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Acknowledgment
  8. References

The use of indoor tanning beds remains prevalent despite increasing data on its harmfulness. A recent survey of adolescents found that 28% of females and 7% of males had used tanning booths repeatedly.1 Evidence is accumulating for the association between tanning bed use and the development of skin cancer.2–9 Tanning bed users are increasingly aware of these risks, although this knowledge may not deter continued use.10–12 Many tanning salon patrons erroneously believe that an artificial tan prevents subsequent sunburn and is safer than tanning outdoors.10,12,13 Tanning bed users report feeling relaxed during indoor tanning,10 and ultraviolet (UV) tanning for habitual users may be considered a substance-related disorder.14

Recent epidemiologic studies have suggested an association between tanning bed/sunlamp exposure and cutaneous melanoma.5–7,9 Because most reports have focused on the “ever-use” of tanning beds,2,4–6 the potential relationship between the extent of tanning bed exposure and the risk of melanoma has not been elucidated in detail. Moreover, previous studies have generally considered only a few confounding factors, including sun sensitivity, sun exposure, and socioeconomic status.3–6 This report further examines the risk of melanoma with tanning bed exposure, and investigates the relationship between the extent of tanning bed exposure and the development of melanoma.

Methods

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Acknowledgment
  8. References

Institutional review board approval was obtained. We sought to enroll a random sample of patients presenting to our academic dermatology clinic over a 12-month period. Surveys were distributed to 1518 patients, and were fully completed by 551 (36.3%). The demographic parameters collected included self-identified race, age, and education level. The surveys assessed the extent of tanning bed exposure, including “ever-use” and use in the last 12 months, age at first exposure, season of use, lifetime number of tanning sessions, minutes spent per session, sun protection attitudes and practices, and leisure and occupational sun exposure. The respondent-reported family history of malignant melanoma (MM) was not assessed because of the potential for inaccuracy. The medical records of respondents were then reviewed for a history of actinic keratosis (AK), basal cell carcinoma (BCC), squamous cell carcinoma (SCC), and MM. Crude model risk estimates, chi-squared analyses, and adjusted model risk estimates with binary logistic regression were performed (SPSS for Windows). P < 0.05 was the threshold for statistical significance.

Confounding variables

Participants were asked a series of questions related to confounding factors in the development of MM. These factors included age, indoor vs. outdoor occupation and leisure activities, Fitzpatrick skin type, history of blistering sunburn, use of sunscreen and sun protective clothing, history of phototherapy, and level of education. Responses to each question were pooled and then categorized (Table 1) for statistical comparison. The incidence of MM was compared for tanning bed users and nontanning bed users overall, and by isolating each potential confounding variable.

Table 1.  Demographic and ultraviolet (UV) exposure characteristics of the study population
CharacteristicNumber (%)
  1. Demographic and UV exposure parameters are shown for 551 patients completing the entire survey. The history of AK and malignancy is shown for 501 of these patients for whom medical records and pathology reports were available. AK, actinic keratosis; BCC, basal cell carcinoma; MM, malignant melanoma; SCC, squamous cell carcinoma.

Gender
 Female337 (61.2)
 Male214 (38.8)
Age (years)
 < 18 48 (8.7)
 18–29103 (18.7)
 30–39 84 (15.2)
 40–49 91 (16.5)
 50–59 84 (15.2)
 > 60141 (25.6)
Race
 Caucasian498
 Asian  7
 Hispanic  7
 African-American  6
 Other/unspecified 33
Tendency to tan
 Easily162 (29.4)
 Moderately222 (40.3)
 Burn rather than tan 80 (14.5)
 Unspecified 87 (15.8)
Education
 High school297 (53.9)
 College121 (22)
 Graduate/professional126 (22.9)
 Unspecified  7 (1.3)
Work Environment
 Indoor359 (65.2)
 Outdoor 45 (8.2)
 Both132 (24.0)
 Unspecified 15 (2.7)
Sunburn in past
 No203 (36.8)
 Yes348 (63.2)
Number of sunburn episodes
 1 72 (20.7)
 2–5196 (56.3)
 6–10 31 (8.9)
 11+ 17 (4.9)
Previous history of
 AK 65 (13)
 BCC 73 (14.6)
 SCC 27 (5.4)
 MM 29 (5.8)

Results

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Acknowledgment
  8. References

Demographics and UV exposure (Table 1)

Surveys were distributed to 1518 patients in the waiting room of our hospital-based clinic, and all surveys were at least partially completed. All surveys were completed with regard to age, gender, tanning bed use, and self-reported diagnosis of melanoma, as these items were listed first; 551 (36.3%) of the patients completed the entire survey, and these surveys were used to tabulate demographic and medical history data (Table 1). Of the 551 patients fully completing the survey, 337 (61.2%) were females and 214 (38.8%) were males; 498 (90.4%) identified themselves as Caucasian. The ages of the participants were well distributed; 297 of the 551 (53.9%) had completed high school, 121 (22%) had completed college, and 126 (22.9%) had completed graduate or professional school. Of the 551 patients, 359 (65.1%) reported an indoor work environment, 45 (8.2%) reported an outdoor work environment, and 132 (24%) reported working both indoors and outdoors; 348 of the 551 participants (63.2%) recalled experiencing sunburn in the past, whereas 203 (36.8%) did not. Of those who had experienced sunburn, over half (196/348, 56.3%) recalled two to five sunburn episodes, 72 (20.7%) reported a single episode, 31 (8.9%) reported six to ten episodes, and 17 (4.9%) reported more than eleven episodes. Of all 551 respondents, 101 (18.3%) reported daily application of sunscreen, 108 (19.6%) reported never using sunscreen, and 335 (60.8%) used sunscreen occasionally.

Incidence of skin cancer and skin premalignancy

Of the 551 patients fully completing the questionnaire, medical records were available for 501 (90.9%). Of these, 65 (13%) had been diagnosed with AKs (mean age, 63.7 ± 11.1 years), 73 (14.6%) with BCC (mean age, 61.6 ± 12.1 years), 27 (5.4%) with SCC (mean age, 64.6 ± 9.7 years), and 29 (5.8%) with MM (mean age, 49.3 ± 15.3 years) (see Table 1).

Tanning bed users

Of the 1518 patients surveyed, 487 (32.1%) reported a history of tanning bed exposure. Women aged 45 years or younger accounted for 60% (292/487) of all tanning bed users, with 59.3% (279/470) of these women reporting a history of tanning bed use compared with 24.4% (108/442) of women aged over 45 years. Subgroup analysis isolating each of the demographic factors and potentially confounding variables did not otherwise predict the utilization of tanning beds.

Incidence of MM

Of the 1518 respondents, 79 (5.2%) reported a previous history of MM. MM was verified via a pathology report in the medical records of 29 of the 501 patients (5.8%) for whom these were available. Of the individuals who had used a tanning bed at least once, 7.0% (34/487) reported a history of MM; in persons who denied the use of tanning beds, 4.4% (45/1031) reported a history of MM (P < 0.05; Table 2). Amongst the entire cohort, the “ever-use” of a tanning bed was a statistically significant risk factor for the development of melanoma [P < 0.05; odds ratio (OR), 1.64; 95% confidence interval (95% CI), 1.01–2.67] (Table 2). In women aged 45 years or younger, the “ever-use” of a tanning bed was an even greater risk factor for the development of melanoma after controlling for the same variables; 18 of 279 women under the age of 45 years who had used a tanning bed reported a previous diagnosis of melanoma, whereas four of 191 women under the age of 45 years who denied ever using a tanning bed reported a previous diagnosis of melanoma (P < 0.05; OR, 3.19; Table 2). Subgroup analysis isolating each of the potentially confounding variables did not reveal any other significant associations with melanoma.

Table 2.  Relationship between reported tanning bed exposure and malignant melanoma
 History of malignant melanoma (%)No history of malignant melanoma (%)Odds ratio (95% CI)
  • CI, confidence interval.

  • *

    P < 0.05 vs. nontanning bed users.

Ever used tanning bed (all respondents; n = 487)34 (7)*453 (93)1.65 (1.01–2.67)
Never used tanning bed (all respondents; n = 1031)45 (4.4)986 (95.6) 
Ever used tanning bed (female respondents age ≤ 45 years; n = 279)18 (6.5)*261 (93.5)3.22 (1.01–11.46)
Never used tanning bed (female respondents age ≤ 45 years; n = 191) 4 (2.1)187 (97.9) 

Duration and number of tanning sessions (Table 3)

Table 3.  Amount of tanning bed use in patients with and without melanoma
 Used tanning beds ≥ 20 sessions (%)Odds ratio (95% CI)Used tanning beds ≥ 20 min per session (%)Odds ratio (95% CI)
  • CI, confidence interval.

  • *

    P < 0.01 vs. no history of melanoma.

Ever used tanning beds (n = 487)
 History of melanoma (n = 34) 21 (62)1.82 (0.85–3.95)16 (48)*3.18 (1.48–6.82)*
 No history of melanoma (n = 453)213 (47) 99 (22) 
Women aged ≤ 45 years (n = 279)
 History of melanoma (n = 18) 14 (78)3.27 (0.97–12.1) 9 (50)*4.12 (1.41–12.02)*
 No history of melanoma (n = 261)135 (52) 51 (19.5) 

Admitted tanning bed users with a history of melanoma were more likely to report greater than 20 tanning bed exposures than were tanning bed users without melanoma [21/34 (61.8%) vs. 213/453 (47.2%)], although this was not statistically significant. Admitted tanning bed users with melanoma reported a significantly greater average time spent per tanning bed session, with 16 of 34 (48%) reporting sessions greater than 20 min, compared with 99 of 453 (22%) tanning bed users with no history of melanoma (P < 0.01; OR, 3.18; 95% CI, 1.48–6.82). Female tanning bed users aged 45 years and younger with a history of MM (n = 18) spent more time per session [9/18 (50%) with sessions averaging over 20 min; P < 0.01] than those with no history of melanoma [51/261 (20%) with sessions averaging over 20 min; P < 0.01; OR, 4.12; 95% CI, 1.41–12.02] (Table 3).

A greater percentage of women aged 45 years and younger with a history of melanoma reported 20 or more lifetime sessions (14/18 or 78%) than did women aged over 45 years without a history of melanoma (135/261 or 52%), although this was not statistically significant.

Discussion

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Acknowledgment
  8. References

In this study, 32% of survey respondents had used a tanning bed at least once, a figure comparable with past studies on tanning bed behavior.7,14,15 Consistent with other studies, tanning bed users were frequently young women.10,14,16–19 We also found evidence of an increasing risk of melanoma with increasing use of tanning beds, as measured by both the number and duration of tanning sessions. In our binary logistic regression analyses of the “ever-use” of a tanning bed and the variables listed above, tanning bed exposure was a significant risk factor for melanoma in all respondents and, in particular, for women aged 45 years and younger. This concurs with several previous studies that have reported a positive association between sunlamp/sunbed use and melanoma.3–6,20,21

A recent meta-analysis of nine case–control studies and one cohort study found a positive association (OR, 1.25) of having ever been exposed to a tanning bed and the risk of melanoma.9 Swerdlow and Weinstock22 reviewed 19 case–control studies examining melanoma and tanning bed exposure. Fewer than half of these studies accounted for confounding factors, and most did not consider the frequency or duration of tanning bed exposure.22 Previous studies in the literature have considered only a few possible confounding factors.3–6,23 Chen et al.7 found that those who first used sunlamps before the age of 25 years had a higher risk for melanoma than those who first used sunlamps later in life. Similarly, Westerdahl et al.20 found that, for those younger than 36 years of age who regularly used an indoor tanning lamp, the risk of melanoma was 8.1 times greater than for “never-users.”

The molecular basis of UV photocarcinogenesis is well known. Most modern tanning units produce mainly UV-A and less than 5% UV-B,13,24,25 although this amount of UV-B irradiation exceeds that in natural sunlight, and is sufficient to suppress cutaneous immunity.26 Bech-Thomsen et al.27 reported a linear relationship between tumor development and the content of UV-B in UV tanning sources. Recently, UV-B has been shown to initiate melanoma in an animal model.28 UV-A radiation penetrates the skin deeply,8,20 causes photoaugmentation and immunosuppression, and induces DNA damage via the production of reactive oxygen molecules.8,29,30 Therefore, it probably plays a contributory role in carcinogenesis.8

Our study has several limitations. Only 36% of the participants completed the survey entirely. The survey was relatively lengthy, was administered in our clinic waiting room, and was collected at the conclusion of the clinic visit. The degree of survey completion related directly to the waiting time, such that the response rate is not surprising. Tanning bed users often sunbathe, making it difficult to separate the effects of artificial and natural UV irradiation. We were unable to control for the use of photosensitizing medications, and survey responses were subject to recall bias. Although we were concerned that the surveyed patients might confuse the diagnosis of MM with other forms of skin cancer, comparison of the survey responses with available pathologic reports (representing about one-third of the respondents) showed good agreement, with a 5–6% incidence of melanoma in both cases. The retrospective nature of the study made it impractical to investigate the lapse of time between tanning bed use and the diagnosis of MM, and whether the diagnosis of melanoma deterred further use of tanning beds in individual patients. Moreover, our results were derived solely from a midwestern academic setting; it is possible that surveys from different climate and practice settings could yield different results.

In conclusion, these results suggest that tanning bed exposure is a significant risk factor for MM, especially in women aged 45 years and younger. This study also correlates the extent of tanning bed exposure and the risk of the development of cutaneous melanoma. These findings reinforce public health urgency to increase the awareness of the potential health hazard of tanning bed exposure.

Acknowledgment

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Acknowledgment
  8. References

Supported by a Skin Cancer Foundation Photobiology grant.

References

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Acknowledgment
  8. References