Diet and cancer: future etiologic research.

In light of several credible diet and cancer hypotheses, we suggest strategies for advancing our understanding in this area. Two conceptual approaches can be taken in defining dietary exposure: the decompositional approach focuses on specific nutrients and other chemical constituents of food, whereas the integrative approach emphasizes the action of whole foods or food patterns (cuisines). Diet-cancer hypotheses can be organized according to this conceptual framework. We review four types of scientific investigation available to us for advancing the diet and cancer field: metabolic (clinical nutrition) studies; animal studies; observational epidemiologic investigations; and clinical trials. Each of these designs has its strengths and limitations. Observational epidemiologic studies and trials have the particular advantage of examining explicit cancer end points in humans. Results from metabolic and animal research, however, can complement the findings from epidemiologic studies and trials. Finally, we briefly review strategies for evaluating promising hypotheses linking diet to cancers of the large bowel, lung, breast, and prostate.