The relationship of occupational and recreational solar ultraviolet radiation with the risk of prostate cancer: A Canadian cohort study.

BACKGROUND

The objective of this study was to examine the relationship of recreational and occupational exposure to solar ultraviolet radiation (UVR) with the risk of developing prostate cancer (PC).

METHODS

Data from three provincial prospective cohorts in Canada (Ontario Health Study, Québec's CARTaGENE, and Alberta's Tomorrow Project) were used. A nested case-cohort approach was applied for the examination of occupational solar UVR and was based on longest held job at baseline. Cox proportional hazards models with age as the time-scale were used to estimate the risk of PC associated with self-reported time spent in the sun and occupational solar UVR (weighted model). Effect modification by body mass index (BMI) was explored.

RESULTS

A total of 543 PC cases were included in the analysis of time spent in the sun and 1667 PC cases were included in the analysis of occupational solar UVR. Compared to < 1 h/day in the sun, 1-< 2 h (Hazard Ratio [HR] 0.96, 95 % CI: 0.81-1.13) and ≥ 2 h (HR 0.89, 95 % CI: 0.76-1.05) were not significantly associated with PC risk. Occupational solar UVR was also not significantly associated with PC risk (HR 1.08, 95 % CI: 0.90-1.30). Compared to < 1 h/day, individuals who spent 1-< 2 h in the sun were at a reduced risk of PC if they had a normal BMI (HR 0.64, 95 % CI: 0.44-0.92), but not if they were overweight (HR 0.99, 95 % CI: 0.76-1.30) or obese (HR 1.20, 95 % CI: 0.90-1.61).

CONCLUSION

Overall, results do not support an association between solar UVR exposure and PC risk, but larger studies are needed to confirm these findings. There is some indication of effect modification by BMI that should be explored in future studies.