The future of molecular epidemiology

Subdomains of epidemiological activity classified according to techniques have been shorter-lived than those classified by the type of disease or exposure. Most of us feel comfortable with broad categories defined by disease group (such as ‘cancer epidemiology’) or by exposure (‘nutritional epidemiology’). In the past, brief vogues for terms such as ‘biochemical epidemiology’ have signalled the availability of new techniques that have been ultimately absorbed into these other entities. Will the term ‘molecular epidemiology’ suffer this fate, or does it imply a paradigm shift that will establish it as a genuine descriptor of a major subdomain of epidemiological activity? A MEDLINE search on the term ‘molecular epidemiology’ reveals over 1600 citations mostly on use of molecular techniques to subtype infectious pathogens. I suspect that infectious disease epidemiologists use the term ‘molecular epidemiology’ to describe this set of techniques, not a paradigm shift in their science. Similarly, they use the term ‘seroepidemiology’ to describe studies using the prevalence of serum antibodies in person, place and time to make inferences about the epidemiology of specific infectious diseases. Sprinkled throughout these citations are chronic disease studies, particularly cancer studies, mainly addressing the use of molecular techniques to make improved or novel assessments of exposures, or to define inherited susceptibility. I will address the applications of molecular techniques to cancer epidemiology, assuming that many of the lessons that can be learned apply to the epidemiology other non-infectious diseases.