Risk of early-onset prostate cancer associated with occupation in the Nordic countries

Abstract

Submitted manuscript version. Published version available in European Journal of Cancer (2017), 87, p. 92-100. ; Background: Early-onset prostate cancer is often more aggressive and may have a different etiology than later-onset prostate cancer, but has been relatively little studied to date. We evaluated occupation in relation to early-onset and later-onset prostate cancer in a large pooled study. Methods: We used occupational information from census data in five Nordic countries from 1960-1990. We identified prostate cancer cases diagnosed from 1961-2005 by linkage of census information to national cancer registries and calculated standardized incidence ratios (SIRs) separately for men aged 30-49 and those aged 50 or older. We also conducted separate analyses by period of follow-up, 1961-1985 and 1986-2005, corresponding to pre- and post-prostatespecific antigen (PSA) screening. Results: For early-onset prostate cancer (n=1,521), we observed the highest SIRs for public safety workers (e.g., firefighters) [SIR=1.71, 95% confidence interval (CI): 1.23-2.31] and military personnel (SIR=1.97, 95% CI: 1.31-2.85). These SIRs were significantly higher than the SIRs for later-onset disease (for public safety workers, SIR=1.10, 95% CI: 1.07-1.14, and for military personnel, SIR=1.09, 95% CI: 1.05- 1.13; pheterogeneity=0.005 and 0.002, respectively). Administrators and technical workers also demonstrated significantly increased risk for early-onset prostate cancer, but the SIRs did not differ from those for later-onset disease (pheterogeneity>0.05). While our early-onset finding for public safety workers was restricted to the post-PSA period, that for military personnel was restricted to the pre-PSA period. Conclusion: Our results suggest that occupational exposures, particularly for military personnel, may be associated with early-onset prostate cancer. Further evaluation is needed to explain these findings.