title: Statistical analysis of molecular epidemiology studies employing case-series.
abstract: The case-series design is being used increasingly to explore associations between environmental risk factors and genetic markers. It is demonstrated that the odds ratio derived from a case-series study is the ratio of the relative risk for developing marker-positive disease to the relative risk for developing marker-negative disease. This parameter is an empirical manifestation of etiological heterogeneity with respect to the risk factor under study, and it can be used to construct a statistical significance test. Presence of etiological heterogeneity, as reflected in departures of this parameter from unity, could be a result of either the presence of distinct causal mechanisms for the two categories of cases, or a different strength of effect via the same mechanism. The case-series approach represents an efficient and valid approach for evaluating gene-environment associations, especially in referral centers where it is difficult to identify a valid control group.
authors.affiliation: Memorial Sloan-Kettering Cancer Center, Department of Epidemiology and Biostatistics, New York, New York 10021.
authors.forename: C B
authors.initials: CB
authors.lastname: Begg
authors.forename: Z F
authors.initials: ZF
authors.lastname: Zhang
mesh_terms: D014408:Biomarkers, Tumor / Q000235:genetics*; D016022:Case-Control Studies; D016001:Confidence Intervals; D005819:Genetic Markers / Q000235:genetics*; D006801:Humans; D008432:Mathematical Computing; D008957:Models, Genetic; D009154:Mutation / Q000235:genetics*; D016273:Occupational Exposure / Q000009:adverse effects*; D016017:Odds Ratio; D016283:Proto-Oncogene Proteins p21(ras) / Q000235:genetics*; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects*; D016159:Tumor Suppressor Protein p53 / Q000235:genetics*; D001749:Urinary Bladder Neoplasms / Q000453:epidemiology / Q000209:etiology / Q000235:genetics*
chemical_list: D014408:Biomarkers, Tumor; D005819:Genetic Markers; D016159:Tumor Suppressor Protein p53; C501009:HRAS protein, human; D016283:Proto-Oncogene Proteins p21(ras)