FOR THE RELATIONSHIP BETWEEN DIET AND CANCER

There have been several advancements in our understanding of cancer at the molecular level. Growth factors, hormones, cytokines, oncogenes, viruses, bacteria, and carcinogens are among the factors that have been identified to initiate and promote cancer [1]. Many of the subcellular mechanisms that promote hyperproliferation, invasion, angiogenesis and metastasis have also been determined. The structure of the entire human genome consisting of almost 25,000 genes as well as the characterization of some of the genes that mediate tumorigenesis is also now evident. Furthermore, there are many advances in our understanding of the control of gene expression in eukaryotic cells that might impact cancer development, including mechanisms regulating chromatin structure and dynamics, epigenetic processes (DNA methylation, histone posttranslational modification), transcription factors, and noncoding RNA. In spite of this significant increase in knowledge about cancer, the application of these advancements to cancer prevention and treatment practice needs greater attention. Moreover, the incidence of certain cancers is projected to increase in the coming decades due to growing and aging populations in many countries. Thus, there is a need for effective preventive strategies for cancer. Importantly, dietary habits are recognized to be important modifiable factors influencing cancer risk and prevention. The World Cancer Research Fund/American Institute of Cancer Research (WCRF/AICR) summary of the available epidemiological evidence on food, nutrition, physical activity, and the prevention of cancer clearly support the suggestion that cancer incidence and death are potentially avoidable by modification of the diet as well as by physical activity [2]. In addition to such observational evidence, both in vitro and in vivo studies have suggested that several bioactive food components, such as phytochemicals found in plants [3] and fungochemicals found in mushrooms [4], are likely to alter susceptibility to cancer. In fact, both essential nutrients and non-essential bioactive food components, have been implicated in altering many of the pathways of cancer, including apoptosis, cell cycle control, differentiation, inflammation, angiogenesis, DNA repair, and carcinogen metabolism [5]. Findings from either human epidemiological or human and animal experimental studies suggest that the study design (e.g., cancer site, model system or population, food constituent and/or total diet composition) may be an important determinant of the direction and magnitude of the response, but variation in biological response may also be involved. Nutritional genomics is an emerging multidisciplinary science that recognizes the potential of nutrients to act as signals to influence cell behavior and also should provide insights about variation in response. For example, variation in genetic influences on the diet due to gene polymorphisms (nutrigenetics) and/or dietary influences on gene expression (nutritional transcriptomics), on DNA methylation and other epigenetic events (nutritional epigenetics) may account EVIDENCE FOR THE RELATIONSHIP BETWEEN DIET AND CANCER