Objectives While several monocyclic aromatic hydrocarbons are classified as definite or possible carcinogens to humans, little data exist on their role in prostate cancer (PCa). We examined occupational exposure to benzene, toluene, xylene (BTX) and styrene and PCa risk in a population-based case–control study in Montreal, Canada.
Methods Cases aged ≤75 years diagnosed with PCa in 2005–2009 (n=1920) and population controls frequency-matched on age (n=1989) provided detailed work histories. Experts evaluated the certainty, frequency and concentration of exposure to monocyclic aromatic hydrocarbons in each job lasting ≥2 years. Logistic regression estimated OR and 95% CIs for PCa risk, adjusting for potential confounders.
Results Exposures to BTX were highly intercorrelated, except for durations of exposure at substantial levels. Ever exposure to any BTX was associated with overall PCa (OR 1.27, 95% CI 1.05 to 1.53), while the OR for styrene was 1.19. However, increases in risk were largely confined to low-grade tumours, with ORs of 1.33 (95%CI 1.08 to 1.64) and 1.41 (95% CI 0.85 to 2.31) for ever exposure to any BTX and styrene, respectively, and a duration response pattern for any BTX. Risks for low-grade tumours were elevated among men exposed ≥25 years at substantial levels of benzene (OR 2.32) and styrene (OR 2.44). Some cumulative exposure categories showed increased risks but without clear trends.
Conclusion Exposure to any BTX was associated with higher risks of overall PCa. Prolonged exposures at the substantial level to benzene and styrene increased risks of low-grade tumours. These novel findings were independent from PCa screening.
- prostate cancer
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Contributors AB-L conducted the data analysis and prepared the manuscript. M-EP conceived and led the PROtEuS study. J-FS and M-EP contributed to the interpretation of the data and critically revised the manuscript. All authors read and approved the final version of the manuscript.
Funding This study was supported financially through grants from the Canadian Cancer Society (grants no. 13149, 19500, 19864 and 19865), the Cancer Research Society, the Fonds de Recherche du Québec—Santé (FRQS), FRQS-Réseau de recherche en santé environnementale and the Ministère du Développement économique, de l’Innovation et de l’Exportation du Québec. M-EP and J-FS received career awards and a fellowship, respectively, from the FRQS.
Competing interests None declared.
Patient consent Not required.
Ethics approval CER – Institut national de la recherche scientifique.
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement Our data can be shared upon agreement with the corresponding author. No additional data are available.
Presented at This work was conducted at INRS-Institut Armand-Frappier, Université du Québec, Laval, Québec, Canada.