Introduction Polycyclic aromatic hydrocarbons (PAHs) have been shown to have endocrine-disrupting effects. Exposure could be carcinogenic to the prostate, a hormone-dependent organ.

Objective To examine the association between lifetime occupational exposure to PAHs and prostate cancer risk.

Methods Face-to-face interviews elicited detailed work histories for 1,937 histologically confirmed prostate cancer cases (524 aggressive) and 1,994 controls from Montreal, Canada. Industrial hygienists applied the hybrid expert assessment approach to assign concentration, frequency and certainty of exposure to benzo(a)pyrene, PAHs from different sources (wood, coal, petroleum, other sources) and PAHs from any source. Odds ratios (ORs) adjusted for age, ancestry, education, lifestyle and occupational factors, and their 95% confidence intervals (CI), were estimated using unconditional logistic regression.

Results After restriction to probable and definite exposure, and application of a 5-year lag, no clear association was observed between exposure to PAHs and overall prostate cancer risk, although a weak positive dose-response pattern emerged for total duration of exposure to PAHs from wood (OR=1.06; 95%CI 0.95 to 1.18, per 5-year increment). Men in the upper tertile of cumulative exposure to these PAHs showed an elevated OR of 1.54 (95%CI 0.60 to 3.92), predominantly reflecting the non-aggressive form of the tumour (OR=1.74; OR=0.67 to 4.56). Nevertheless, exposure to PAHs from wood occurring at least 10 years before the index date was associated with some elevated risks of high-grade tumours (OR=1.54, 95%CI 0.70–3.39). Similar results were found in sensitivity analyses, including those restricted to controls recently screened for prostate cancer or in those prioritizing the Gleason score ascertained from prostatectomy over that from biopsy.

Conclusion Only a handful of small studies have used detailed exposure assessment protocols to study the role of PAHs in prostate cancer risk. Our findings provide some limited evidence that exposure to PAHs from wood increases the risk of prostate cancer.