Abstract 635: Indoor tanning and risk of early-onset basal cell carcinoma

Abstract

Abstract Background: Basal cell carcinoma (BCC) is the most common cancer in the United States, with more than two million BCCs diagnosed annually. In recent decades, incidence of BCC has been increasing, particularly among adults under age 40 and especially in young women. Parallel to this incidence trend has been an increase in the popularity of indoor tanning. Although the International Agency for Research on Cancer recently concluded there was “convincing evidence to support a causal association” between indoor tanning and melanoma and squamous cell skin cancer, there was only very limited and inconsistent data for BCC. Methods: We examined indoor tanning in relation to early-onset BCC in the Yale Study of Skin Health in Young People. BCC cases (n=376) and controls with minor benign skin conditions (n=390) under age 40 were identified through Yale Dermatopathology between 2006 and 2010. Approximately two-thirds of dermatologists in Connecticut send their biopsied tissue to Yale dermatopathologists for diagnosis. Controls were frequency matched to cases on age, gender, and body site of biopsy. Participants provided information on ever indoor tanning, age of initiation, frequency, duration, burns while tanning, and type of tanning device during an in-person interview. We calculated odds ratios (OR) and 95% confidence intervals (CI) using multivariate logistic regression with never indoor tanners as the referent group. Results: Ever indoor tanning was associated with a 69% increased risk of early-onset BCC (95% CI = 1.15-2.48); this association was stronger among women (OR = 2.14, 95% CI = 1.31-3.47). The risk from indoor tanning was largely confined to BCCs on the trunk and extremities (OR = 2.81, 95% C I= 1.57-5.02) as opposed to BCCs on the head/neck (OR = 1.11, 95% CI = 0.66-1.86). Indoor tanning was also more strongly associated with multiple BCC (two or more BCCs; 37% of cases) case status (OR = 2.16, 95% CI = 1.26-3.70) than single BCC case status (OR = 1.46, 95% CI = 0.96-2.22). Risk increased dose-dependently with years used regular indoor tanning devices (p-trend = 0.003), number of overall burns (p-trend = <0.001) and burns to biopsy site (p-trend = <0.001) from indoor tanning. Approximately 27% of total early-onset BCC cases (or 43% among women) could be prevented if individuals never tanned indoors. Conclusions: Indoor tanning was a strong risk factor for early-onset BCC, particularly among women. While replication in other populations is necessary to confirm the positive association we observed between indoor tanning and early-onset BCC, our results fulfill many of the criteria for causality including biologic plausibility, strength of the association, dose-response effects, specificity to body sites most uniquely exposed to indoor tanning, and coherent findings with melanoma studies. Indoor tanning should continue to be targeted by both policy-based and behavioral interventions, as the impact on BCC-associated morbidity may be substantial. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 635. doi:1538-7445.AM2012-635