Little data exist on prostate cancer (PCa) risk associated with exposure to monocyclic aromatic hydrocarbons (MAHs), although several of them are classified as definite or possible carcinogens to humans. We examined PCa risk in relation to lifetime occupational exposure to benzene, toluene, xylene and styrene in a population-based case-control study in Montreal, Canada.
Incident cases diagnosed with PCa between 2005 and 2009 (n=1902, aged ≤75 years) and population controls frequency-matched on age (n=1958) provided detailed work histories during in-person interviews. Chemists evaluated the certainty, frequency and concentration of exposure to chemical agents in each job held using semi-quantitative indicators. Logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (CI) for PCa risk, adjusting for several potential confounders.
Applying a 5 year lag, the proportions of subjects ever exposed to MAHs (any), benzene, toluene, xylene and styrene were 31%, 11%, 12%, 10% and 2%, respectively. The risk of aggressive PCa (Gleason score >7 or [4+3]) was not increased with greater duration of exposure or with cumulative exposure to any of the MAHs. However, the risk of non-aggressive PCa was increased with ≥25 years of exposure to any (OR=1.59, 95% CI:1.09–2.34) or substantial (OR=2.34, 95% CI:1.22–4.50) level of benzene, to substantial level of styrene (OR=2.44,95%CI:1.16–5.13), and with high cumulative exposure to benzene (OR=1.68,95%CI:1.16–2.44] or xylene (OR=1.51,95%CI:1.01–2.25). Similar results were observed in the subset of subjects recently screened for PCa.
Our results suggest that high duration and level of exposure to benzene, xylene or styrene may increase the risk of non-aggressive PCa.