Abstract 4651: Interaction between outdoor ultraviolet radiation and indoor tanning bed use on skin cancer risk

Abstract

Abstract Background: Solar ultraviolet (UV) radiation and the use of UV-emitting tanning devices are risk factors for melanoma and non-melanoma skin cancer (NMSC). Despite abundant evidence, frequent outdoor sunbathers are more likely to use indoor tanning beds. In our study, we aim to investigate the interaction between indoor tanning bed use and exposure to solar UV radiation associated with the risk of skin cancer. Methods: The study population was participants of the Nurses' Health Study II, which started in 1989 including 116,430 registered female nurses aged 25-42. Participants biennially self-reported diagnosis of skin cancer: melanoma, basal cell carcinoma (BCC), and squamous cell carcinoma (SCC). Cases for melanoma and SCC were confirmed by medical records. Information on indoor tanning bed use during high school/college or age 25-35 was collected. Cumulative average UV exposure at residence during follow-up was calculated for each participant. We built Cox proportional hazards models adjusting for potential confounders. Interactions between cumulative UV exposure and indoor tanning use were tested in multivariable-adjusted models for three types of skin cancer. Results: We found significant interactions between cumulative average UV during follow-up and indoor tanning bed use during high school/college years (P for interaction=0.01) on the risk of BCC, but not during the age 25-35 (P for interaction=0.15). Subjects who were exposed to high UV and used tanning bed during high school/college (RR: 1.54, 95% CI 1.38, 1.72) or during age 25-35 (RR: 1.56, 95% CI: 1.43, 1.69) had nearly 50% increased risk of BCC compared to subjects who were exposed to low UV and did not use tanning bed. Increased risk but non-significant interactions were found for SCC (indoor tanning during high school/college years: P for interaction=0.29, during age 25-35: P for interaction=0.09). Subjects who were exposed to high UV and used tanning bed during age 25-35 had approximately double the risk of SCC (RR: 2.04, 95% CI: 1.51, 2.76), compared to the reference group. No significant interactions were found for the risk of melanoma. Conclusions: We found significant interaction between outdoor UV and indoor tanning bed use during high school/college years on the risk of BCC but not SCC or melanoma. Citation Format: Jongeun Rhee, Tricia Li, Wen-Qing Li, Abrar A. Qureshi, Eunyoung Cho. Interaction between outdoor ultraviolet radiation and indoor tanning bed use on skin cancer risk [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4651.