Biomarkers in occupational cancer epidemiology: considerations in study design

Epidemiologic studies of occupational groups have been central to the identification of human carcinogens. The incorporation of a biochemical component into occupational studies of cancer can expand the possibilities for identifying human carcinogens and for understanding the disease process. Two epidemiologic studies of occupation and cancer which include evaluation of biomarkers are described. The association of acetylator phenotype with bladder cancer risk was studied in benzidine-exposed workers. The association of benzene-related leukopenia with leukemia is being studied in benzene-exposed workers. These investigations illustrate issues in the use of biomarkers in epidemiologic studies of cancer risk. Such studies require the identification and characterization of the population at risk. Disease susceptibility factors are amenable for inclusion in these studies and can be statistically modeled as exposure-effect modifiers. Biomarkers of exposure are mainly of importance in short-term longitudinal and cross-sectional studies of exposure and intermediate outcomes and for validation of other data sources. Several sources of error can affect the results of molecular epidemiologic studies. Aside from minimizing laboratory error, consideration must be given in the design and execution of these studies to potential problems in subject selection and field collection of biologic samples and other relevant data.