A multifaceted perspective on skin cancer prevention

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.