Cancer due to asbestos exposure.

To determine the relationship between malignancies and asbestos exposure, the number of asbestos bodies in wet lung tissue was counted by light microscopy according to the modified method of Smith and Naylor, and occupational histories were examined. The results revealed that 17 (89 percent) of 19 malignant mesotheliomas, 39 (38 percent) of 104 lung cancers, 23 (37 percent) of 62 gastric cancers, and 13 (28 percent) of 45 colon cancers were shown to be cases with asbestos exposure. These values were significantly higher than those of noncancerous cases (200 cases). It is of interest that five out of ten cases of leukemia were related to asbestos exposure. Nearly all multiple cancers including lung and gastric cancer in this study were also cases with asbestos exposure. Additional research should be conducted on the carcinogenicity of asbestos for multiple cancers.