Diet and cancer prevention: evidence-based medicine to genomic medicine.

The practice of medicine, including health promotion and disease prevention, is on the verge of being revolutionized once again as the scientific and medical community transitions from evidence-based medicine to genomic medicine. Evidence-based medicine entails the systematic approach of formulating a question, developing literature search strategies, and evaluating and applying evidence to establish clinical practice guidelines. In 1982, when the National Research Council published the first comprehensive review of diet and cancer, the literature was primarily based on epidemiological studies, comparing dietary patterns between countries of low and high incidence for particular cancers. The American Institute for Cancer Research conducted an evidence-based review of the world literature and issued its first report in 1997, and the National Cancer Institute followed with evidence-based overviews of cancer prevention. The World Health Organization International Agency for Research on Cancer recently published a series of handbooks on cancer prevention in relation to dietary factors. The expert recommendations stemming from this extensive evidence subsequently influenced the clinical practice of medicine. In 2001, the complete sequencing of the human genome signified the beginning of the postgenomic era, in which new approaches and technologies are causing a shift in biomedical research. A widening understanding of the complex interactions among genotype, diet, lifestyle, and environment has evoked a change in clinical medical practice, where the evidence- and population-based protocol is evolving into a more personalized system that includes the analysis of individual genotype and phenotype. The implications of this evolution are considerable, because genomic medicine has the potential to give rise to personalized nutrition recommendations and specialized medical treatment.