Lung cancer risk among pneumoconiosis patients in Japan, with special reference to silicotics

A cohort study was conducted on 3335 hospitalized male pneumoconiosis patients in order to determine their lung cancer mortality. The patients were collected from 11 hospitals specializing in the treatment of pneumoconiosis and other occupational diseases and injuries, and were followed up during 1979-1983. Age-adjusted expected numbers were calculated using the mortality of the general population as a standard. A significantly high O/E ratio (4.80) for lung cancer was observed, particularly among silicotics (6.03). A slightly more than two-fold increase in risk for lung cancer was found among those who had never smoked. No dose-response relationship was found between lung cancer mortality and duration of dusty work or radiographic categories. A nested case-control analysis showed work experience in the ceramics industry to be a risk factor for lung cancer.