Objectives Preventable risk factors for prostate cancer are poorly understood; sun exposure is a possible protective factor. The goal of this study was to investigate prostate cancer risk in outdoor workers, a population with high sun exposure.
Methods Prostate cancer cases and controls from a large study (conducted between 1994 and 1997) were used for this analysis. A job exposure matrix (JEM) was used to assign solar ultraviolet radiation (UVR) at work as moderate (2 to <6 hours outside/day) or high (≥6 hours). Average daily satellite UV-B measures were linked to the latitude/longitude of the residences of each participant. Several other exposure metrics were also examined, including ever/never exposed and standard erythemal dose by years (SED×years). Logistic regression was used to evaluate the association between solar UVR exposure and the odds of prostate cancer.
Results A total of 1638 cases and 1697 controls were included. Men of Indian and Asian descent had reduced odds of prostate cancer (ORs 0.17 (0.08 to 0.35) and 0.25 (0.15 to 0.41), respectively) compared with Caucasian men, as did single men (OR 0.76 (0.58 to 0.98)) compared with married men. Overall, no statistically significant associations were observed between sun exposure and prostate cancer with 1 exception. In the satellite-enhanced JEM that considered exposure in high category jobs only, prostate cancer odds in the highest quartile of cumulative exposure was decreased compared with unexposed men (OR 0.68 (0.51 to 0.92)).
Conclusions This study found limited evidence for an association with prostate cancer, with the exception of 1 statistically significant finding of a decreased risk among workers with the longest term and highest sun exposure.
- Solar radiation
- Outdoor workers
- Prostate cancer
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Contributors CEP led the study as part of her PhD work, including data acquisition, cleaning and analysis, and wrote the manuscript. PAD, SK and A-MN were on CEP's supervisory committee during this work, and gave methodological guidance in the design phase of the work through to its completion; all also provided a critical review and comments on the manuscript drafts. PH worked on the ultraviolet radiation exposure assessment using satellite data, both in planning it as well as in generating the files; he also provided critical feedback on the manuscript. PJV is the data steward for the case–control study on which the manuscript is based and provided feedback at the study design stage, as well as on the manuscript drafts. NK was on the Canadian Cancer Registries Board which was responsible for the design and implementation of the case–control study, and she also provided critical feedback on the manuscript. MWK supervised the work, helped to design the analytical strategy and helped with interpretation of results; she too reviewed and critiqued the manuscript.
Funding CEP was supported by doctoral fellowships from the Michael Smith Foundation for Health Research, the Canadian Institutes of Health Research Skin Research Training Centre and the Canadian Institutes of Health Research Institute of Gender and Health.
Competing interests None declared.
Patient consent Obtained.
Ethics approval University of British Columbia Behavioural Research Ethics Board.
Provenance and peer review Not commissioned; externally peer reviewed.
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