The epidemiology of lung cancer in metropolitan Detroit: Racial differences in men.

Abstract

Etiology of the excess and increasing lung cancer incidence rates in African-American men compared to white men is obscure. Although the causative role of cigarette smoking is indisputable, the prevalence and effects of other putative risk factors, for example, environmental and occupational exposures, remain to be characterized. The purpose of this population-based case-control study was to investigate the relationship between the incidence of primary lung cancer and various factors, including smoking, in black and white males residing in Metropolitan Detroit. Lung cancer cases and a comparison group of colon and rectal cancer cases, diagnosed in 1984 through 1987, provided lifetime smoking and occupational histories as well as demographic, residential, and medical information in telephone interviews. Results demonstrated the strong association of cigarette smoking with lung cancer with no racial disparity in the magnitude of risk. Among never-smokers, black males were twice as likely to develop lung cancer as white never-smokers and, in men with chronic respiratory disease prior to lung cancer diagnosis, the risk was substantially elevated in black never-smokers. Patterns of employment indicated more blacks worked as service workers, nonfarm laborers, and operatives. Excess risk, adjusted for age and cigarette smoking, was noted in truck drivers, auto mechanics, and men employed in the construction and agricultural industries with no racial diversity. Conversely, black employees in the automobile manufacturing industry were at higher risk of lung cancer with a significantly elevated risk seen in furnace operators who were exclusively black. Inadequate numbers precluded meaningful racial comparisons of histopathological patterns associated with occupational exposures. Distribution of cell types differed in never-smokers: squamous cell carcinoma was diagnosed in higher proportion than adenocarcinoma in blacks while adenocarcinoma predominated in whites. In summary, confirmation of known risk factors indicated that this study population and methodology are suitable for further etiological research. Notable racial differences in risk in never-smokers suggested that studies in never-smokers could be promising for developing a better understanding of respiratory carcinogenesis.