world cancer report - iarc

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