world cancer report - iarc

Fig. 2.3 Smoking by children is increasing worldwide.
Fig. 2.4 A young man smoking a hookah
(Bangladesh).
consumption (Fig. 2.6). The risk is also
proportional to the duration of smoking.
Hence, the annual death rate from lung
cancer among 55-64 year-olds who
smoked 21-39 cigarettes daily is about
three times higher for those who started
smoking at age 15 than for those who
started at age 25.
Intensity of exposure to tobacco smoke is
determined by the smoking device used
(cigarette, cigar, pipe, hookah, etc.) and, for
any one method, may be determined by the
“depth” of inhalation. Smoking of black
tobacco cigarettes represents a greater
risk for most tobacco-related cancers than
smoking of blond cigarettes. Similarly, filtered
and low-tar cigarettes entail a lower
risk for most tobacco-related cancers than
unfiltered and high-tar cigarettes. However,
a “safe” cigarette does not exist; all smoking
tobacco products entail a carcinogenic
risk. Taken together, the epidemiological
data summarized above establish “causation”
because of the consistency of results,
the strength of the relationship, its specificity,
the temporal sequence between
exposure and disease and the dose—
response relationship.
24 The causes of cancer
Fig. 2.5 Mortality due to lung cancer is decreasing in men in most industrialized countries, an exception
being Hungary, which now has the highest rates of lung cancer mortality in the world.
Within many communities, smoking, and
hence lung cancer, are sharply related to
social class [7]. Between communities
worldwide, incidence of lung cancer varies
dramatically. High rates are observed in
parts of North America, while developing
countries have the lowest rates (Fig. 2.7).
In the USA, Europe and Japan, 83-92% of
lung cancer in men and 57-80% of lung cancer
in women is tobacco-related. A maximal
impact of lung cancer occurs when the
population has attained a maximal prevalence
of smoking that has continued
throughout most of the life span of the
smokers. As the prevalence of smoking
increases, it is likely that an epidemic of
lung cancer will sweep the developing
world in the coming decades [8].
In addition to lung cancer, smoking causes
cancers of the larynx, oral cavity, pharynx,
oesophagus, pancreas, kidney and bladder
[2] (Table 2.3). Dose-response relationships
between number of cigarettes smoked and
risks for developing these cancers have
been found consistently. Most data involve
cigarette smoking but, for example, cigar
and pipe smoking present a greater risk for
cancer of the oral cavity than does cigarette
smoking. For cancer of the bladder
and kidney, risks vary with the duration and
intensity of smoking, but are lower than
those for lung cancer. In non-alcohol drink-