Lung cancer: is the etiology changing?

A 16-year study of lung carcinomas seen at the Department of Pulmonary Medicine in Uppsala, Sweden, was studied retrospectively. The material was divided into four 4-year periods, which were compared with respect to the occurrence of pleural plaques, occupational and smoking history, and histological type of tumor. There were 205 women and 897 men with acceptable x-rays of the chest. Of the women, 27% of those up to age 70 were smokers in the first period and 70 in the last. Among men, the smoking habits remained the same with 95-97% smokers or exsmokers. Asbestos exposure, as judged from the pleural plaques and the occupational history, showed a highly significant increase among the men during the period. Only one of 77 patients with pleural plaques had never smoked. Tobacco thus remains the main carcinogen for lung cancer, but seems to be increasingly dependent on cocarcinogens. Among men with pleural plaques, there were relatively more adenocarcinomas than expected.