LAUSR

Skin cancer is the most common malignancy in the USA, with over five million new diagnoses estimated in 2016 alone [1], and the incidence of melanoma, the deadliest form of skin cancer, doubled from 1982 to 2011 [2]. Of particular concern is the overwhelming increase in melanoma rates among adolescents and young adults [3]. A recent study analyzing Surveillance, Epidemiology, and End Results (SEER) data from 1973 to 2011 found that melanoma incidence among individuals in these age groups (0–14 and 15– 39 years old) had increased by 253%, with young women at the greatest risk of developing melanoma [4]. Indoor tanning (IT) devices, common sources of ultraviolet (UV) radiation, appear to have played a significant role in the rising rates of melanoma and other skin cancers in recent decades, particularly among young women [5–7]. Previous research has conclusively determined that exposure to IT increases melanoma risk and the existence of a dose-response relationship between IT and increased risk [5]. Such risks have led to the classification of IT devices as, Bcarcinogenic to humans,^ by the World Health Organization’s International Agency for Research on Cancer [8, 9]. Additionally, in 2014, the U.S. Food and Drug Administration (FDA) reclassified IT devices as moderateto high-risk medical devices (class II) and required all IT devices to display a black box warning stating they should not be used by individuals under 18 years of age [10]. However, despite the demonstrated dangers of this behavior, IT remains common in the USA and several other countries, particularly among teenage girls and young women. Much recent attention has focused on ITon or around college campuses, where rates exceed 40% according to data from a recent systematic review and metaanalysis [11]. We examined time of IT initiation (history and current use) in college students. We conducted a study of undergraduate students from three colleges in the USA (in Massachusetts and Alabama). A crosssectional survey was administered in March–April 2014 using convenience sampling, a technique commonly employed in college tanning studies [12]. The institutional review boards of participating institutions granted the study exempt approval. Data obtained included demographics and tanning behaviors (including ever IT, currently IT, age of initiation, and frequency in past year) [15, 16]. Of 1014 surveys received, 971 met eligibility criteria (age 18 years or older and undergraduate enrollment at one of the participating institutions). Of these, 837 (86.1%) reported past IT practices (including none) and were included for analysis (80% female; 73% self-identified white; median age 20 years). Of the 837 respondents, 256 (30.6%) reported ever IT: 10.5% began before high school and 73.0% started during high school. Among these 256 who ever tanned, 135 (52.7%) reported IT in the past year; of these, 91% reported initiating IT in or before high school. Regarding frequency, individuals initiating IT before high school were 2.9 times (95% confidence interval [CI] [1.08–7.82]) more likely to have indoor tanned 10+ times in the past year compared with those starting in high school or college. Students at the two institutions in Alabama were significantly more likely to have engaged in IT than students at the university in Massachusetts (adjusted odds ratio [AOR] = 3.21, 95% CI [2.09–4.94] and AOR = 7.31, 95% CI [4.25–12.59], respectively). Mitchell Cancer Institute, University of South Alabama, 1660 Springhill Avenue, Mobile, AL 36604-1405, USA Department of Psychiatry & Behavioral Sciences, Memorial Sloan-Kettering Cancer Center, New York, NY, USA Department of Communication Studies, Northeastern University, Boston, MA, USA Department of Social and Behavioral Sciences, Harvard T.H. Chan School of Public Health, Boston, MA, USA Correspondence to: C Daniel [email protected]