[Occupational exposure and histologic differentiation of lung cancer. Retrospective assessment in Cracow]

A population-based case-control study was performed in Cracow, Poland. Male cases and controls were identified from the Cracow Death Register. Information were obtained by mailed questionnaire from next-of-kin on smoking, occupational branch, occupational exposures and other pertinent variables. Response rates were 73.5% in cases and 72.0% in controls. For cases that underwent a bronchial biopsy or surgical excision the histological diagnosis of the tumor was obtained from clinical records. The case group contained 343 subjects with squamous cell carcinomas, 151 small cell carcinomas and 106 adenocarcinomas. 27 cases showed other histological types (large cell carcinoma and not classifiable). Analysis was performed separately by histological type for occupational exposure variables adjusted for smoking. Long-term exposure to mineral dust and metal dust (20 years or more) was found to be a significant risk factor for small cell and squamous cell carcinoma. The effect was more pronounced if the analysis was restricted to the age groups "less than 70 years". The highest relative risk due to occupational exposures was found for squamous cell carcinoma and mineral dust exposure for more than 20 years (RR = 2.45, 95% CI 1.43-4.19). The estimated effect of mineral dust on small cell carcinoma and adenocarcinoma was slightly lower (RR = 2.29, 95% CI 1.16-4.53 and RR = 2.04, 95% CI 0.89-4.64, respectively). The effect of metal dust and fumes appeared to be about the same for squamous and small cell carcinoma.