A multifaceted perspective on skin cancer prevention

Abstract

Solar ultraviolet radiation has been acknowledged as the main culprit for the three major types of skin cancer which are among the most numerous (basal cell carcinoma [BCC], squamous cell carcinoma [SCC]) and most dangerous (cutaneous malignant melanoma) malignancies in Caucasian populations. The present thesis comprises six individual projects providing a multifaceted perspective on the prevention of these tumours. Project I evaluated a school-based sun safety education programme developed by the Swiss Cancer Leagues. Primary school students in the Canton of Zurich (North-Eastern Switzerland) were asked to answer a questionnaire regarding their sun-related knowledge, behaviour, and sunburn experience shortly before and one year after the intervention (repeated cross- sectional assessment). Based on the data from more than 3000 students, the sun safety education programme was effective in sustainably improving children’s sun-related knowledge and possibly to some extent in decreasing sunburn rates, but had no obvious impact on the examined sun protective behaviours (use of sunscreen, seeking shade). Project II represents a systematic review of cross-sectional and interventional studies on sun-related knowledge, attitudes, and protective behaviours of outdoor workers. The 52 relevant publications identified through an electronic search of medical literature databases (PubMed, Embase, PsycINFO) and an extensive hand search suggested that outdoor workers’ sun protective behaviours are largely inadequate and sunburn rates are high (50-80% per season). However, there is evidence that sun safety education in outdoor occupational settings is effective in increasing workers’ protective behaviours and presumably also in reducing sunburn incidence. Project III investigated sun protective behaviour and sunburn experience of vacationers spending holidays in the tropics or subtropics. The 1165 standardised face-to-face interviews conducted among air passengers waiting in the departure or baggage claim area at the Airport Basel-Mulhouse (Switzerland/France) and among vacationers waiting for pre-travel health advice at the Travel Clinic of the Swiss Tropical and Public Health Institute Basel (Switzerland) revealed that almost all respondents used sunscreen at the holiday destination. Nevertheless, wearing a sunhat and protective clothing as well as seeking shade were clearly less common sun protection methods. The assessed sunburn rate among the 324 interviewed returning air passengers was alarmingly high, with 44% having suffered from sunburn during their holiday stay. Project IV comprehensively analysed the content and quality of 2103 print media articles pertaining to skin cancer prevention and related topics (solaria, vitamin D) published in Germany and Switzerland over a one-year period (2012-2013). Whereas skin cancer secondary prevention received little press attention, primary prevention was a frequently covered media topic. However, the delivered information was generally rather superficial. By far the most common and often sole sun protection recommendation made was the use of sunscreen. In total, 27% of all analysed articles contained misleading or erroneous statements which were mostly related to the use of sunscreen and vitamin D issues. Projects V and VI are based on data derived from the Clinical Practice Research Datalink, a large, well-validated primary care database established in the United Kingdom (UK). Project V estimated BCC incidence in the UK and characterised affected patients regarding lifestyle factors and comorbidities. The calculated age-standardised BCC incidence in adults rose from 119 to 165 per 100 000 person-years between the years 2000 and 2011. According to the matched case-control analysis including 57 121 BCC cases and 57 121 BCC-free controls, BCC risk was slightly increased in alcohol drinkers, but reduced in smokers and in individuals with a body mass index outside the normal range. BCC was associated with various comorbidities related to iatrogenic or non-iatrogenic immunosuppression. Project VI explored whether patients regularly exposed to systemic nonsteroidal anti- inflammatory drugs (NSAIDs) are at a reduced risk of nonmelanoma skin cancer (NMSC). The matched case-control analysis comprised 65 398 BCC cases, 65 398 BCC-free controls, 7864 SCC cases, and 31 456 SCC-free controls. Overall, NSAID use was not negatively associated with BCC, but when looking exclusively at users of single NSAID substances there was a suggestion of a reduced BCC risk in regular users of aspirin and ibuprofen. SCC risk was slightly decreased in regular users of any NSAIDs, with the strongest risk reduction observed in current users of coxibs. These findings provide evidence that patients predisposed to NMSC may benefit from chemoprevention with NSAIDs.