Aerodigestive and gastrointestinal tract cancers and exposure to crocidolite (blue asbestos): incidence and mortality among former crocidolite workers.

The objective of this article was to assess the association between the incidence and mortality from aerodigestive cancers and exposure to crocidolite (blue asbestos). Our study is a cohort study of former workers of the now-defunct crocidolite mining and milling operation at Wittenoom, Western Australia, who have been followed up since 1979 and on whom asbestos exposure and smoking information was known. Standardised mortality and incidence rates were used to compare former workers with the Western Australian male population. Cases were matched with up to 10 randomly assigned controls, and conditional logistic regression was used to examine the relationship between asbestos exposure, smoking status and cancer incidence. There were 129 incident cases from all cancers of interest and 57 deaths. Former workers had a significantly higher risk of mortality from upper aerodigestive cancers than the Western Australian male population. The incidence of upper and lower aerodigestive cancers was higher in the Wittenoom cohort but not significantly so. Cumulative exposure to asbestos did not appear to be associated with the incidence of stomach cancer, colorectal cancer or upper aerodigestive cancers. Smoking status was strongly associated with the incidence of upper aerodigestive cancers, with current smokers experiencing the greatest risk. Our study with longer and more complete follow-up, smoking information and a stronger study design does not show an association between cumulative asbestos exposure and stomach cancer or other gastrointestinal cancers. The excess mortality from upper aerodigestive cancers seen in this cohort of former asbestos workers compared to the Western Australian male population does not appear to be associated with exposure to crocidolite. Copyright 2004 Wiley-Liss, Inc.