Study finds Norwegian offshore petroleum workers at greater risk of skin cancer

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Summary

This cohort study compared the incidence of skin cancer (melanoma and squamous cell carcinoma, SCC) in Norwegian offshore petroleum workers to a range of ultraviolet radiation (UVR) exposure activities. The cohort, which included 27,917 men and women, was established in 1998 and followed till 2017 to ascertain the incidence of skin cancer. UVR exposure was estimated via a self-reported questionnaire that obtained information on sunbathing and indoor tanning habits, frequency of sunburns and on residential and occupational solar UVR exposure. The questionnaire also gathered data on sunscreen use. The authors reported that melanoma risk increased with higher sunbathing frequency after the age of 20, intensity of sunburn and, surprisingly, higher sunscreen use. SCC risk increased with indoor tanning frequency after the age of 20, sunburn intensity and, again, higher sunscreen use. Based on the results the authors concluded that this occupational group could benefit from targeted sun protection advice.

Link to study

Ultraviolet radiation and risk of cutaneous melanoma and squamous cell carcinoma in males and females in the Norwegian Offshore Petroleum Workers cohort

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Comments by ARPANSA

Most of the results of this study were not statistically significant which may have been due to the limited skin cancer case numbers overall and consequently in each exposure category. Regardless, the findings are generally supported by the results of other similar studies from Canada, Australia and the United Kingdom (Schnatter et al. 1992, Gun et al. 2006, Stenehjem et al. 2014). The strengths of this study include high quality cancer data within the cohort and the inclusion of a comprehensive set of UVR exposure variables to conduct exposure specific analysis of skin cancer risk. However, despite questionnaires being completed before disease diagnoses, the authors could not rule out the potential for confounding through self-reported lifestyle habits. In addition, crude categories of UVR exposure may have led to differential misclassification (which could have under- or over-estimated the resulting risk estimates). The authors argue that the increased risk of skin cancer found among higher users of sunscreen could indicate a “desire to tan” or a higher exposure to solar UVR through more frequent outdoor activity. Further, this finding may also serve to reiterate that application of sunscreen is only part of the sun protection measures advised by ARPANSA and other health authorities, and cannot be relied on alone to prevent skin cancer.

Overall, the results of this study support the advice from both ARPANSA and Cancer Council Australia about limiting UV exposure and applying sun protection measures. Despite some of the limitations described by the authors, this study added to the body of evidence that UVR exposure is a causal factor in the development of SCC and melanoma.