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Discuss the mechanisms by which diet plays a role in carcinogenesis.

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Introduction

Kerri Alldis. Cell Biology Of Cancer Essay. October 2003. Discuss the mechanisms by which diet plays a role in carcinogenesis. Carcinogenesis is the process by which cancers, a set of diseases characterised by unregulated cell growth, are generated. This is a multi-step mechanism (King, Roger.J.B., 2002). The uncontrolled growth of cells results in the formation of tumours (National Institute On Alcohol Abuse, 1993). Cancer is termed 'metastatic' meaning that it can be spread around the body and is caused by a genetic mutation; therefore cancer is defined as a genetic disease at the cellular level. There are three stages in cancer development, initiation via the genetic mutation, promotion where the initiated cell is stimulated to divide, and progression where tumours are produced as the cancer spreads (National Institute On Alcohol Abuse, 1993). There is strong evidence linking diet with several cancer types especially in the digestive (gastrointestinal) tract but also in the breast, lung and prostate which do not come into direct contact with food consumed (King, Roger.J.B., 2000). It is thought that diet may be involved at each stage of carcinogenesis, for example, contaminants in food such as nitrosamines or polycyclic aromatic hydrocarbons (PAH's) are initiators, and some fats are known to be promoters (Professor Marcel Roberfroid., University Of Louvain Belgium., 2000). Food components that are relative to carcinogenesis can be divided into macro-components that tend to act indirectly and micro-components, which have a clearly defined action - they act directly. ...read more.

Middle

Odds ratios and 95% confidence intervals were calculated. It was concluded from the investigation that red meat consumption was associated with an increased risk of lung cancer (Michael, C.R. et al., 2001). New Zealand has the highest mortality rate of colon cancer, second highest of breast cancer and the third highest of prostate cancer. There is a possible association with heterocyclic amine consumption from locally cooked meat for each of these cancers (Ferguson, L.R., 2002). Heterocyclic amines (HCA's) are formed during the high temperature cooking of meat. Animal studies have shown that different HCA's have different target sites causing cancers of the liver, colon, breast and prostate. Cured meats such as bacon may contain potentially carcinogenic nitrosamines, which have been shown experimentally to induce tumours in various organs (Ferguson, L.R., 2002). It has been suggested that deaths from breast cancer may be linked to fat consumption in USA, Netherlands, UK, and Italy. Animal feeding experiments show a causal relationship between fat intake and cancer (King, Roger.J.B., 2002). Dietary fat is regarded as one of the major risk factors in cancers of the breast, colon and prostate. It has been reported that fats that contain high concentrations of n-6 polyunsaturated fatty acids (n-6PUFA) promoted the development of mammary tumours. These n-6 fatty acids enhance the incidence, growth and metastasis of the tumours (Malgorzata Jelinska et al., 2003). ...read more.

Conclusion

et al., 1997). Arsenic is a carcinogen reportedly responsible for lung and skin cancers. In Bangladesh, humans are being exposed to arsenic by ingestion of contaminated water. Evidence shows that once absorbed, arsenic can be oxidised and/or methylated in the human body. In vitro studies have indicated that arsenic can interfere with DNA replication, DNA repair and cell division (Masud Karin., 2000). Obesity increases the risk of breast cancer in premenopausal women, probably by increasing serum concentrations of bioavailable oestradiol. Nutrition might affect breast cancer risk by altering levels of growth factors such as insulin-like growth factor-1 (Key, T.J. et al., 2003). It has been indicated that diet may affect the relationship of GSTP1, EPHX1 and GSTM1 polymorphisms to lung cancer risk (Ya-Yu Tsai et al., 2003). As well as the cooking of food, storage and preservation are important. Poor storage leads to fungal growth such as Aspergillus flavus, which produces aflatoxin B - a carcinogen that produces liver tumours. Nitrates used in preservation such as E251 and E252 are converted to n-nitrosocompounds in the gut. These are potential carcinogens that have been suggested to cause stomach cancer. In conclusion, the study of the link between diet and cancer is a complex issue. A wide range of foods have a range of effects upon various cancers by several mechanisms. Knowing the mechanisms by which diet affects carcinogenesis means that many cancers could be prevented or at least reduced just by a change of lifestyle with respect to diet. ...read more.

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