world cancer report - iarc
world cancer report - iarc
world cancer report - iarc
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level the dose—response relationship is<br />
less clearly defined. The magnitude of<br />
increased risk associated with a particular<br />
rate of alcohol consumption varies for<br />
each tumour type. The risk of head and<br />
neck <strong>cancer</strong> is 5-10 times higher in heavy<br />
drinkers than in abstainers, the carcinogenic<br />
effect of alcohol appearing to be<br />
more potent in the oral cavity, pharynx<br />
and oesophagus and weaker in the larynx.<br />
The relative risk of breast <strong>cancer</strong> in<br />
women with a high consumption of alcohol<br />
is approximately two-fold.<br />
Most available data concerning the carcinogenic<br />
role of alcohol in humans are<br />
derived from epidemiological studies<br />
based on interviews or similar approaches.<br />
Since alcohol drinking carries a strong<br />
social stigma in many populations, it is<br />
likely that individuals underestimate and<br />
under-<strong>report</strong> their intake of alcohol, particularly<br />
in the case of heavy consumption.<br />
Under-<strong>report</strong>ing of alcohol drinking,<br />
resulting in the classification of heavy<br />
drinkers as light- or non-drinkers, would<br />
result in underestimation of the actual<br />
carcinogenic effect of the habit. It is possible<br />
therefore that the role of alcohol in<br />
human <strong>cancer</strong> is greater than commonly<br />
perceived.<br />
Alcohol drinking and tobacco smoking<br />
show a synergistic interaction in the etiol-<br />
Years Disability-<br />
Region % of deaths of life lost adjusted years<br />
life lost<br />
Latin America 4.5 5.9 9.7<br />
Sub-Saharan Africa 2.1 2.0 2.6<br />
Other Asian countries 1.8 1.6 2.8<br />
Former socialist countries 1.4 5.7 8.3<br />
China 1.3 1.8 2.3<br />
Industrialized countries 1.2 5.1 10.3<br />
India 1.2 1.4 1.6<br />
Middle East 0.1 0.2 0.4<br />
Overall 1.5 2.1 3.5<br />
Table 2.5 Percentage of the population dying from alcohol-associated diseases in different <strong>world</strong> regions,<br />
and the respective years of life lost .<br />
Cancer Men Women<br />
Table 2.6 Percentage and number of <strong>cancer</strong> cases <strong>world</strong>wide attributable to alcohol consumption, 1990.<br />
30 The causes of <strong>cancer</strong><br />
% No. of cases % No. of cases<br />
Oral cavity & pharynx 23 51,000 15 12,700<br />
Oesophagus 24 51,800 14 14,500<br />
Liver 10 30,100 6 7,300<br />
Larynx 22 26,500 14 2,500<br />
Breast - - 3 26,800<br />
Total 4 159,400 2 63,800<br />
ogy of <strong>cancer</strong>s of the oral cavity, pharynx,<br />
larynx and oesophagus; the risk of <strong>cancer</strong><br />
for heavy consumers of both products relative<br />
to that for subjects who neither<br />
smoke nor drink is higher than the product<br />
of the risks attributable respectively to<br />
heavy drinking and heavy smoking separately<br />
(Fig. 2.14) [5]. Very heavy drinkers<br />
(e.g. alcoholics), among whom alcohol can<br />
be the source of up to 30% of total calorie<br />
intake, tend to have a diet poor in fruit and<br />
vegetables, which may further enhance<br />
their risk of developing these <strong>cancer</strong>s.<br />
Relatively few studies have examined possible<br />
variations in risk attributable to different<br />
alcoholic beverages: evidence on<br />
T<br />
Fig. 2.11 Computed tomography (CT) scan of an<br />
oesophageal tumour (T). Heavy alcohol drinking is<br />
a major risk factor.<br />
Alcohol dehydrogenase<br />
Alternative pathways:<br />
Cytochrome P450 (CYP2E1)<br />
and catalase<br />
Acetaldehyde<br />
dehydrogenase<br />
CH 3CH 2OH<br />
CH 3CHO<br />
CH 3COOH<br />
C0 2 +H 2O<br />
Ethanol<br />
NAD +<br />
NADH + H +<br />
Acetaldehyde<br />
Acetatic acid<br />
Carbon dioxide<br />
+water<br />
Fig. 2.12 The major pathway of alcohol metabolism<br />
in humans.