The attribution of lung cancers to asbestos exposure: A pathologic study of 924 unselected cases

We studied a series of 924 nonselected surgical cases of lung carcinoma (without occupational history in clinical records) by histologic examination and light microscopic determination of asbestos body (AB) concentration to determine cancers attributable to asbestos exposure. Lower lobes showed higher concentrations, but no significant associations were recorded between concentrations and histologic type of the lung carcinomas. Histologic asbestosis was demonstrated in 56 cases considered definitely asbestos-related. In 12 of them, the demonstration of asbestosis was attained only after repeated examination of additional sections, suggested by the finding of more than 1,000 ABs per gram of dry weight (gdw), an indicator of occupational asbestos exposure. In the 56 cases, the median AB concentration was 3,281/gdw. In 5 other cases without demonstration of ABs in histologic sections, concentrations higher than this median and interstitial fibrosis were observed. The AB count after digestion of pulmonary tissue may show greater sensitivity than the search in histologic sections as an indicator of substantial asbestos exposure. Extrapolation of our estimate on a national scale suggests about 2,000 cases per year of asbestos-related cancers of the lung in Italy; 281 cases were reported (from all occupational causes) in the years 1990-1995.