Biology of Cancer and AIDS
•
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
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:
•
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
Induces
cytochrome
to activate
carcinogens
Carcinogen
(binds to DNA
)
alter expression of
oncogenes and tumor
suppressor genes
Mechanism of action
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
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
