PROGRESSION OF ASBESTOSIS PREDICTS LUNG-CANCER

Study objectives: To explore whether the progression of asbestosis cor relates with the risk of lung cancer among patients with asbestosis. D esign: A group of 85 asbestosis patients (78 men and 7 women) were rad iographically followed up between 1979 and 1987, Two or three posteroa nterior radiographs taken from each patient in 1978 to 1979, 1983 to 1 984, and 1986 to 1987 were classified according to the International L abour Office 1980 classification and were used to divide the patients into progressors and nonprogressors. Follow-up for cancer was done aut omatically through the files of the Finnish Cancer Registry from the t ime of determination of the progression status to December 31, 1994. P redictors of lung cancer risk were studied with a logistic regression model, and the standardized incidence ratio (SIR) was calculated for l ung cancer. Results: Of the 24 male patients with progressive small op acity profusion, 11 (46%) developed lung cancer, as opposed to 5 (9%) of the 54 male patients without progression. The SIR for lung cancer w as 37 (95% confidence interval, 18 to 66) for the progressors and 4.3 (1.4 to 9.9) for the nonprogressors. In both groups, all the lung canc er cases occurred among smokers or ex-smokers. None of the seven femal e patients showed progressive small opacity profusion. One of them dev eloped lung cancer, In the logistic regression model including all 85 asbestosis patients, radiographic progression of small opacity profusi on (p=0.0009) and current smoking (0.0021) were significant predictors of lung cancer morbidity, Conclusions: Asbestosis patients with radio graphic progression of small opacity profusion over a few years are at a higher risk of lung cancer than those with a less aggressive course of the disease, The progression of pulmonary fibrosis may be an indep endent risk factor that, in addition to smoking history and the intens ity of asbestos exposure, could be used to estimate lung cancer risk.