OBJECTIVES The aim of the study was to investigate the asbestos-associated risk of lung cancer according to histological type of cancer, lobe of origin, pulmonary concentration, and type of amphibole fibers and also to estimate the etiologic fraction of asbestos for lung cancer.

METHODS The pulmonary concentration of asbestos fibers in 113 surgically treated male lung cancer patients and 297 autopsy cases among men serving as referents was determined by scanning electron microscopy. The age- and smoking-adjusted odds ratios of lung cancer were calculated according to pulmonary fiber concentration for all lung cancer types, squamous-cell carcinoma, and adenocarcinoma and for the lower-lobe and the upper- and middle-lobe cancers.

RESULTS The risk of lung cancer was increased according to the pulmonary concentration of asbestos fibers (f) of 1.0 to 4.99 x 10(6) f.g-1 [odds ratio (OR) 1.7] and > or = 5.0 x 10(6) f.g-1 (OR 5.3). The odds ratios associated with fiber concentrations of > or = 1.0 x 10(6) f.g-1 were higher for adenocarcinoma (OR 4.0) than for squamous-cell carcinoma (OR 1.6). The asbestos-associated risk was higher for lower lobe tumors than for upper lobe tumors. The risk estimates for anthophyllite and crocidolite-amosite fibers were similar, except for the risk of squamous-cell carcinoma. An etiologic fraction of 19% was calculated for asbestos among male surgical lung cancer patients in the greater Helsinki area.

CONCLUSIONS Past exposure to asbestos is a significant factor in the etiology of lung cancer in southern Finland. The asbestos-associated risk seems to be higher for pulmonary adenocarcinoma and lower-lobe tumors than for squamous-cell carcinoma and upper-lobe tumors.