Lect_16_HR _Alcohol and cancer_post - Biology of Cancer and AIDS Bottom Line Alcohol consumption is associated with increased risk of some but not all

Lect_16_HR _Alcohol and cancer_post - Biology of Cancer and...

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Biology of Cancer and AIDS
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Alcohol consumption is associated with increased risk of some, but not all cancers, most notably cancers of the oral cavity and pharynx, esophagus, larynx, breast and liver. V Bagnardi et al. A meta-analysis of alcohol drinking and cancer risk. British Journal of Cancer 2001 85: 1700-1705. Alcohol has many potential pathways to lead to cancer Alcohol itself is not a mutagen, but associated acetaldehyde may be Moderate alcohol consumption (2 drinks/day) is associated with a 25% decreased risk of heart disease So, if you are gonna drink, keep it to 2 for men and 1 for women Bottom Line
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World Cancer Research Fund cancer preventability estimates from alcohol intake Cancer USA (%) UK (%) China (%) Esophagus 34 51 11 Mouth, Pharynx & Larynx 27 41 10 Liver 15 17 6 Colorectum 5 7 1 Breast 11 22 1 Source:
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Repeated exposure to alcohol cause tissue damage and cell death in areas of the body with direct alcohol contact. In response, surviving cells grow and replace destroyed cells. Thus, the ability to trigger cell proliferation is one mechanism by which alcohol causes cancer Ethanol (acetaldehyde) is human carcinogen Ethanol metabolism activates other pro-carcinogens (e.g. Reactive Oxygen Species – destructive to DNA) Disrupts folate metabolism- important in DNA synthesis and repair Suppresses the immune system which may facilitate tumour cell spread Mechanism of action
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Induces cytochrome to activate carcinogens Carcinogen (binds to DNA ) alter expression of oncogenes and tumor suppressor genes Mechanism of action
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Cancer Site Cases Relative risk 1 drink =12 oz beer, 5 oz wine, or 1.5 oz 80-proof liquor 2 drinks/day 4/day 8/day Oral cavity and pharynx 7,954 1.8 2.9 6.0 Oesophagus 7,239 1.5 2.2 4.2 Larynx 3,759 1.4 1.9 4.0 Breast 44,033 1.3 1.7 2.7 Liver 2,294 1.2 1.4 1.9 Colon and rectum 11,296 1.1 1.2 1.4 Stomach 4,518 1.1 1.2 1.3 Ovary 1,651 no association 1.2 1.5 Prostate 4,094 no association 1.1 1.2 Relative Risks of Alcohol Consumption and Site-specific Cancers
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Mechanism by Site Digestive tract cancers: Variation in ethanol metabolising enzymes (ADH, ALDH) modulates cancer risk Oral cavity, larynx, pharynx and esophagus cancers: Synergistic effect of carcinogens in tobacco and alcoholic drinks lead to mucosal hyperproliferation Breast cancer : Increases estrogen and androgen levels/induces expression of
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