Relation between asbestosis and bronchial cancer in amphibole asbestos miners.

Relation between asbestosis and bronchial cancer in amphibole asbestos miners Sir-Sluis-Cremer and Bezuidenhout (1989;46:537-40) present data on the relation between asbestosis and bronchial cancer in amphibole miners but analyse the effect of dose of asbestos only after allowing for the effect of asbestosis grade. Since the risk and severity of asbestosis are themselves dose related much of the effect of dose on the risk of cancer had already been allowed for by the analysis ofthe effect of asbestosis grade. Nevertheless, years of exposure, probably the most reliable measure of dose because it is known more accurately than intensity, still had a significant effect. This is consistent with the dose of asbestos rather than asbestosis being the major determinant of the risk of cancer. It would be interesting to see the results of a further analysis of the data in which the various measures of dose were entered into the logistic regression before the asbestosis grade to determine the effect of asbestosis after the effect of dose of asbestos has been allowed for. To shed further light on the relation between asbestosis and bronchial cancer the ideal analysis would compare the incidence ofcancer in subjects with and without asbestosis matched for dose of asbestos received. I wonder whether their data include sufficient subjects to attempt such an analysis? Their analysis concerned subjects who had undergone necropsy, which occurred in a minority of deaths in the study population. The criteria for selection for necropsy were not mentioned. If necropsy had been more; 103-ATC-13.1.90likely to be carried out in men with cancer ifthere had also been evidence ofasbestosis during life, as has been the case in the United Kingdom until recently, this would have tended to augment the apparent effect of asbestosis on the risk of cancer. It is not indicated whether the presence of asbestosis was assessed without knowledge of whether or not cancer was present. Pathologists commonly look harder for asbestosis when they know bronchial cancer is present. Table 2 of the paper shows that there were large standard deviations in the various measures of dose and suggests that subjects with only brief exposure were included. The observation that there appeared to be no excess risk of cancer in the group without asbestosis may indicate no