Histologic type of lung cancer and asbestos exposure.

The histologic types of lung cancer in 855 patients (747 men and 107 women) from three hospitals and one international study of insulation workers were evaluated. Of these, 196 cases had asbestos exposure. About one half of the cases were diagnosed from surgical slides and one half from autopsy slides. Squamous cell carcinoma constituted the largest percentage of tumor types and was found with the same frequency in exposed and nonexposed groups. Small cell carcinoma was found in 25% of the exposed and in 15% of the nonexposed patients. Upper lung sites were involved in about two thirds of the cases with asbestos exposure and lower lobes in the other one third. There was little difference in histologic type in cases regardless of whether upper or lower lobes were involved. Cigarette smokers who smoked until their cancer diagnosis showed no difference in histologic type by amount smoked, and slight but not statistically significant differences from ex-cigarette smokers.