Cancer
Occupational exposure to asbestos and risk of bladder cancer Sarina D. Murray* Sarina Murray Murray Murray Murray Murray Murray Murray Occupational and Environmental Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute
Bladder cancer is the 10th most common cancer worldwide, occurring mainly in men over 65 and in white populations. About half of the cases are attributable to tobacco smoking, with occupational exposures accounting for ~20-25% of cases among men. Evidence on asbestos-related bladder cancer risk remains inconclusive, largely due to limited individual-level data and insufficient adjustment for smoking and other high-risk occupations. We assessed occupational asbestos exposure and bladder cancer risk among 1182 cases and 1408 controls in the New England Bladder Cancer Study, adjusting for age, race, sex, smoking, and high-risk occupations. Exposure was estimated from lifetime job histories using a job-exposure matrix. Participants were classified as ever exposed if they held any job with ≥25% exposure probability. Cumulative exposure was calculated as the sum of intensity of exposure (1–5–25 scale) multiplied by job duration, with jobs below the probability threshold assigned zero. Adjusted OR and 95% CIs were estimated using logistic regression models. Ever exposure to chrysotile asbestos (270 cases (22.8%) and 241 controls (17.1%) was associated with increased bladder cancer risk (OR = 2.10, 95% CI: 1.56–2.82). Cumulative exposure showed a significant exposure–response trend across quartiles (ORQ1vsUnexposed = 1.96, 95% CI: 1.27-3.04; ORQ2vsUnexposed = 1.93, 95% CI: 1.29-3.07; ORQ3vsUnexposed = 2.02, 95% CI: 1.31-3.12; and ORQ4vsUnexposed = 2.4, 95% CI: 1.58-3.65, p-trend=0.0001). Amphibole asbestos metrics were highly correlated with chrysotile asbestos, as all amphibole-exposed participants were also exposed to chrysotile asbestos. Adjusting for other bladder cancer–related occupational exposures (metalworking fluids, diesel exhaust, solvents) did not materially alter risk estimates. Although evidence remains limited, our findings suggest an independent exposure–response relationship between asbestos and bladder cancer, improving understanding of its etiology.