ABSTRACT
There is a wide range of biomarkers that can be used in population-based molecular
epidemiological studies of cancer. These include biomarkers of exposure, intermediate
endpoints (e.g., biomarkers of early biological effect), disease, and susceptibility (1-7)
(Fig. 1). Hypothesis-driven biomarkers have been used for many years in molecular
epidemiology studies of cancer (e.g., measurement of xenobiotics and endogenous
carcinogens, macromolecular adducts, cytogenetic endpoints in cultured lymphocytes,
DNA mutations in tumor suppressor genes, and phenotypic and genotypic measures of
genetic variation in candidate genes). Perhaps the most revolutionary change that has
occurred in molecular epidemiology in the past several years has been the emergence of
discovery technologies that can been incorporated into a variety of study designs and
include genome-wide scans of common genetic variants, messenger RNA (mRNA) and
microRNA expression arrays, proteomics, and metabolomics (also referred to as
metabonomics) (8-14). These approaches are allowing investigators to explore biological
responses to exogenous and endogenous exposures, to evaluate potential modification of
those responses by variants in essentially the entire genome, and to define tumors at the
chromosomal, DNA, RNA, and protein levels. At the same time, with the incorporation of
more powerful technologies into molecular epidemiology studies, there has been greater
concern that the rights and confidentiality of study subjects be protected. A discussion of
informed consent is outside the scope of this chapter, but we do note the critical need to
consider ethical issues and informed consent procedures at the outset of designing a study.
