This guide was compiled after recommendations by the American Institute for Cancer Research (AICR) Cancer Resource Advisory Council. It encompasses the AICR position on current issues in nutrition for cancer survivors during treatment and is intended to provide advice about dietary supplements for cancer survivors who are still being treated. Current scientific findings about the safety and effectiveness of some commonly used dietary antioxidants and nonantioxidant supplements during chemotherapy are presented and assessed. Use of dietary supplements during cancer treatment remains controversial. Patients are cautioned that vitamin and mineral supplements as therapies are not substitutes for established medicine. The current recommendation for cancer patients is to only take moderate doses of supplements because evidence from human clinical studies that confirm their safety and benefits is limited. A daily multivitamin containing supplements at the levels of the Dietary Reference Intakes can be used safely as part of a program of healthy nutrition. In addition, the AICR Cancer Resource Advisory Council concluded that further scientific research is needed to provide a set of firm guidelines for the use of vitamin and mineral supplements by cancer patients during treatment.

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The genomic era of human nutrition is upon us: the human genome and several plant genomes have been characterized, and genetically modified foods are now abundantly available in the marketplace. The link between diet and cancer is well established, and new genomic technologies have made possible the investigation of nutritional modulation of the carcinogenesis pathway with nutrients, micronutrients, and phytochemicals. Current study of nutrient-modulated carcinogenesis involves exploring the effect of nutrients on DNA damage and repair mechanisms; DNA methylation, which influences gene expression and cellular phenotypes; antioxidant rearranging and oxidative stress; target receptors and signal transduction pathways; cell cycle controls and check points; apoptosis; and antiangiogenic processes. With nutritional genomics, proteomics, and metabolomics, scientists are able to simultaneously elucidate the biological effects of dietary constituents on cell function and global gene expression. This generation of new knowledge on nutrient-gene interactions provides the justification for a research framework for diet and cancer prevention that is focused on identifying and developing new biomarkers as well as a novel and contemporary paradigm for dietary intervention.

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.

Since the national declaration of the war on cancer three decades ago, research on carcinogenesis has yielded a tremendous knowledge base on cancer. Cancer cells are the result of multiple genetic defects resulting from exposure to environmental, dietary and infectious agents. Multistep and multistage carcinogenesis may span 20 y or more, a time that provides research and clinical opportunities to suppress this disease in its early and premalignant stages before clinical symptomatic, invasive stages. Where do we go from here? After this year's milestone of gene sequencing accomplishments, further research opportunities arise in pursuing studies on the mechanisms of the acquired capacities of cancer cells, including their limitless replicative potential, sustained angiogenesis and invasion and avoidance of apoptosis. With new DNA chip technology and functional proteomics, complex nutrient-gene interactions may now be investigated. Research on nutrient-gene interactions not only provides pathophysiologic mechanisms of cancer causation and prevention, but also improves the ability to conduct cancer surveillance, crucial in identifying at-risk populations. By combining chemoprevention approaches, from the use of single nutrients to multiple dietary constituents and functional foods, the scope of future cancer prevention strategies will be broadened. Research on eating behavior and changing dietary patterns must be included in any cancer prevention strategy. A new paradigm for diet, nutrition and cancer prevention can be developed using multidisciplinary approaches that include lifestyle and environmental changes, dietary modifications and physical activity consciousness to reduce the burden of cancer not only for high risk individuals but for the general population as well.