Using data from the SYNERGY project, we evaluated the association between occupational exposure to polycyclic aromatic hydrocarbons (PAH) and the risk of lung cancer, adjusted for tobacco smoking.Methods
For 16 901 lung cancer cases and 20 965 matched population or hospital controls, PAH exposure was estimated using a quantitative general population job-exposure matrix (‘SYNJEM’) based on five-digit ISCO-68 codes (4639 cases, 4713 controls ever exposed). Odds ratios (ORs) and 95% confidence intervals (95% CI) were estimated using unconditional logistic regression models adjusted for age, sex, study centre, smoking behaviour, and ever employment in an occupation with known lung cancer risk.Results
We observed a modest increased risk of lung cancer associated with occupational exposure to PAHs according to various exposure metrics (ever/never, duration, cumulative dose, time since last exposure). The ORs for ever exposure to PAH were 1.09 (95%CI, 1.04–1.15) overall, 1.08 (95%CI, 1.02–1.15) in men, 1.20 (95%CI, 1.05–1.38) in women, and 1.04 (95%CI, 0.88–1.22) in never smokers. These results are further supported by significant exposure response-relationships (p-value for trend <0.05 for years of employment and cumulative exposure [(BaP) µg/m3-years]). When stratified by histological subtype, increased risks and positive exposure response-relationships were apparent only for squamous cell carcinoma and small cell lung cancer.Conclusions
Our pooled analysis suggests that occupational exposure to PAH is associated with a modest increase in the risk of lung cancer, after adjustment for tobacco smoking and exposure to other occupational lung carcinogens.