Cancer is now considered a chronic disease of the genome that may be influenced at many stages in its natural history by nutritional and metabolic factors that affect not only the prevention but also the progression and treatment of this devastating disease.
The cancer phenotype is the result of the interaction of both genetic and environmental influences and most of the evidence for this is drawn on studies of human populations as well as from animal experiments that model the process of carcinogenesis. Perhaps the strongest evidence of environmental influence is that of diet. It is estimated that up to 80 percent of colon, breast, and prostate cancer cases and one third of all cancer cases may be influenced by diet and associated lifestyle factors.
All classical nutrient categories consist of bioactive dietary compounds, including carbohydrates, amino acids, fatty acids and structural lipids, mineral, and vitamins. In addition, there is an extensive list of non-nutrient componenets, particularly phytochemicals, which can have anti-cancer activity. Phytochemicals are components of plant-based diet that possess substantial anticarcinogenic and anti-mutagenic properties. An estimated 25,000 different chemical compounds occur in fruits, vegetables, and other plants eaten by humans. They can encompass such diverse chemical classes as carotenoids, flavonoids, organosulfur compounds, isothiocynates indoles, monoterpenes, pehnolic acids, and chlorophyll. Most of these nutrients can influence gene expression of steps along the genotype-phenotype continuum.
Dietary habits continue to surface as significant factors that may influence cancer incidence and tumor behavior. Nutritional programming in utero has a major impact on the development of chronic illnesses in later life. Therefore, it is essential to measure new biomarkers of nutrient-gene interaction in the genotype-phenotype continuum at different stages of our life cycle. Expanding knowledge based on ‘omic’ responses across tissues and integrated through systems biology potentially will provide the specificity and sensitivity of responses to bioactive food constituencies, identify biomarkers, and identify responders and nonresponders to a particular diet. Therefore, nutritional genomics has far-reaching potential in the prevention of diet-related diseases and provides a new frontier, challenges, and opportunities in moving nutrition towards individualized health.
With the advent of the postgenomic era, biological and medical research and clinical practice has witnessed an explosion in strategies and goals. This eventually will revolutionized the classical practice of nutrition from the current evidence-based medicine towards genomic-based medicine. To accomplish this goal we need appropriate bioinformatics to analyze data obtained by each "omic" technology and need to be able to integrate the findings obtained from genomic, proteomic, and metabolic measurements into a coherent application database to address the genotype-phenotype relationship.
Information stored in a database can only serve the needs of science once they are coordinated with other clinical variables such as personal and family history, physical examinations, and laboratory and functional imaging information of the individual. This is the great challenge ahead of us but this is also a great opportunity in the dawn of nutritional genomics.