Asbestos, asbestosis, smoking, and lung cancer. New findings from the North American insulator cohort

Am J Respir Crit Care Med. 2013 Jul 1;188(1):90-6. doi: 10.1164/rccm.201302-0257OC.


Rationale: Asbestos, smoking, and asbestosis increase lung cancer risk in incompletely elucidated ways. Smoking cessation among asbestos-exposed cohorts has been little studied.

Objectives: To measure the contributions of asbestos exposure, asbestosis, smoking, and their interactions to lung cancer risk in an asbestos-exposed cohort and to describe their reduction in lung cancer risk when they stop smoking.

Methods: We examined lung cancer mortality obtained through the National Death Index for 1981 to 2008 for 2,377 male North American insulators for whom chest X-ray, spirometric, occupational, and smoking data were collected in 1981 to 1983 and for 54,243 non-asbestos-exposed blue collar male workers from Cancer Prevention Study II for whom occupational and smoking data were collected in 1982.

Measurements and main results: Lung cancer caused 339 (19%) insulator deaths. Lung cancer mortality was increased by asbestos exposure alone among nonsmokers (rate ratio = 3.6 [95% confidence interval (CI), 1.7-7.6]), by asbestosis among nonsmokers (rate ratio = 7.40 [95% CI, 4.0-13.7]), and by smoking without asbestos exposure (rate ratio = 10.3 [95% CI, 8.8-12.2]). The joint effect of smoking and asbestos alone was additive (rate ratio = 14.4 [95% CI, 10.7-19.4]) and with asbestosis, supra-additive (rate ratio = 36.8 [95% CI, 30.1-45.0]). Insulator lung cancer mortality halved within 10 years of smoking cessation and converged with that of never-smokers 30 years after smoking cessation.

Conclusions: Asbestos increases lung cancer mortality among nonsmokers. Asbestosis further increases the lung cancer risk and, considered jointly with smoking, has a supra-additive effect. Insulators benefit greatly by quitting smoking.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Asbestos / adverse effects*
  • Asbestosis / epidemiology*
  • Causality
  • Cohort Studies
  • Follow-Up Studies
  • Humans
  • Lung Neoplasms / epidemiology*
  • Male
  • Middle Aged
  • North America / epidemiology
  • Occupational Exposure / statistics & numerical data
  • Risk Factors
  • Smoking / epidemiology*
  • Smoking Cessation / statistics & numerical data
  • Survival Analysis


  • Asbestos