Insulation, asbestos, smoking habits, and lung cancer cell types

The association between occupational exposure to asbestos and histological type of lung cancer was analyzed in a multicenter hospital-based case-control study (2,871 male cases and 5,240 male controls) conducted from 1981-1991. Twenty-two percent of cases and 18% of controls were employed in asbestos-related occupations for at least 1 year. Most of these asbestos jobs were in the construction field. The odds ratio (OR) among current smokers was 1.0 [95% confidence intervals (CI) 0.9 to 1.3]; for ex-smokers, the OR was 1.4 (95% CI 1.1 to 1.6). In contrast, 10% of cases and 5% of controls self-reported that they were chronically exposed to asbestos for at least 1 year. Self-reported asbestos exposure was significantly related to all lung cancer cell types among smokers and ex-smokers, although a trend in the ORs with duration of self-reported exposure was not found for current smokers. Among 48 cases and 52 controls reporting distinct exposure to building insulation, the OR was 2.2 (95% CI 1.2 to 4.3) for current smokers, and 1.8 (95% CI 0.9 to 3.6) for ex-smokers, compared to subjects who were not exposed to building insulation and asbestos. A nonsignificant association with self-reported exposure to asbestos was observed for a small number of never smokers (eight of 83 nonsmoking cases, OR = 2.0, 95% CI 0.9 to 4.6). When examining these results and their causal implications, possible misclassification and reporting biases need to be considered.