Journal Article

Predictors of Lung Cancer among Asbestos-exposed Men in the β-Carotene and Retinol Efficacy Trial

Mark R. Cullen, Matt J. Barnett, John R. Balmes, Brenda Cartmel, Carrie A. Redlich, Carl A. Brodkin, Scott Barnhart, Linda Rosenstock, Gary E. Goodman, Sam P. Hammar, Mark D. Thornquist and Gilbert S. Omenn

in American Journal of Epidemiology

Published on behalf of Johns Hopkins Bloomberg School of Public Health

Volume 161, issue 3, pages 260-270
Published in print February 2005 | ISSN: 0002-9262
Published online February 2005 | e-ISSN: 1476-6256 | DOI:
Predictors of Lung Cancer among Asbestos-exposed Men in the β-Carotene and Retinol Efficacy Trial

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Despite numerous published studies, debate continues regarding the risk of developing lung cancer among men exposed occupationally to asbestos, particularly those without radiographic or functional evidence of asbestosis. The β-Carotene and Retinol Efficacy Trial (CARET), a study of vitamin supplementation for chemoprevention of lung cancer, has followed 4,060 heavily exposed US men for 9–17 years. Lung cancer incidence for 1989–2002 was analyzed using a stratified proportional hazards model. The study confirmed excessive rates of lung cancer among men with radiographic asbestosis. Comparison of study arms revealed a strong, unanticipated synergy between radiographic profusion category and the active intervention. In the large subgroup of men with normal lung parenchyma on chest radiograph at baseline, there was evidence of exposure-related lung cancer risk: Men with more than 40 years’ exposure in high-risk trades had a risk approximately fivefold higher than men with 5–10 years, after adjustment for covariates. The effect in these men was independent of study intervention arm, but pleural plaques on the baseline radiograph and abnormal baseline flow rate were strong independent predictors of subsequent lung cancer. Residual confounding by subclinical asbestosis, exposure to unmeasured lung carcinogens, or differences in smoking are unlikely to explain these observations better than a carcinogenic effect of asbestos per se.

Keywords: asbestos; asbestosis; beta carotene; clinical trial [publication type]; lung neoplasms; occupational exposure; vitamin A; CARET, β-Carotene and Retinol Efficacy Trial; FEV1, forced expiratory volume in 1 second; FVC, forced vital capacity; ILO, International Labour Organization.

Journal Article.  8294 words.  Illustrated.

Subjects: Public Health and Epidemiology

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