Abstract B86: Indoor tanning use and incidence of skin cancer

Abstract

Abstract Tanning beds are used by 30 million Americans each year. The use of tanning beds has been shown to increase the risk of skin cancers in previous epidemiological studies. A 2007 meta-analysis by the International Agency for Research on Cancer (IARC) reported positive associations of ever-use of tanning beds with increased risks of melanoma and squamous cell carcinoma (SCC). In 2009, the IARC classified UV radiation from tanning beds as human carcinogen (group 1). However, risk effect of indoor tanning on basal cell carcinoma (BCC), the most prevalent skin cancer in Caucasians, has been inconclusive. Besides, evidence for a dose-response relationship with melanoma and SCC was inconsistent across previous studies. In this study, using a large and well-characterized cohort in the U.S., the Nurses' Health Study II, we followed up 73,494 female nurses for 20 years and investigated the frequency of tanning bed use during high school/college, at age 25–35, as well as the overall average usage during both periods in relation to three types of skin cancer (BCC, melanoma, and SCC). We used Cox proportional hazards models to calculate the hazard ratios (HR) and 95% confidence intervals (CI) for each type of skin cancer. During follow-up, 5,526 BCC cases, 348 melanoma cases, and 400 SCC cases developed. We found highly significantly elevated risk of BCC among participants who used tanning beds either during high school/college or at ages 25–35 (p < 0.001). The multivariable-adjusted HR for 1 time/year use was 1.10 (95% CI 1.08–1.12) with the use during high school/college and 1.06 (95% CI 1.04–1.07) with the use at ages 25–35. A dose-response effect was detected for all three types of skin cancers, with the multivariable-adjusted HRs for average 1 time/year use during both periods of 1.04 (95% CI, 1.03–1.05; p < 0.001) for BCC, 1.03 (95% CI, 0.995 − 1.06; p = 0.09) for melanoma, and 1.05 (95% CI, 1.02–1.08; p = 0.002) for SCC. Compared to individuals who used tanning beds from ages 25–35, we found a significantly higher risk of BCC for those who used it during high school/college (p for heterogeneity = 0.002). Of note, for those with > 6 times/year use, the multivariable-adjusted HR of BCC compared to non-users was 1.35 (95% CI, 1.23–1.49) at ages 25–35 and 1.82 (95% CI, 1.60–2.08) during high school/college (p for heterogeneity < 0.001). Our data provide strong evidence for an association between tanning bed use and the risk of skin cancers with a dose-response effect, especially for BCC. Citation Information: Cancer Prev Res 2011;4(10 Suppl):B86.