world cancer report - iarc

TOBACCO CONTROL
SUMMARY
> Tobacco-induced death and disease are
preventable: halving current smoking
rates would avoid 20-30 million deaths
before 2025 and 150 million by 2050.
> Smoking cessation is very effective in
reducing the risk of lunb cancer even in
later life.
> The greatest saving of life would result if
rates of smoking uptake by children and
adolescents were decreased.
> Comprehensive tobacco control, including
implementation of regulatory measures
and encouraging personal commitment,
requires coordinated involvement
of government and community organizations,
health care professionals and
planners.
> The hazard posed by environmental
tobacco smoke is significant. This justifies
the demand for a tobacco-free
environment, particularly at work and
in public places.
Tobacco usage was estimated to account
for an annual death toll of more than three
million in 1990 (Table 4.1). The latest estimates
from WHO put the annual number
of deaths today at more than four million.
If current smoking patterns continue, the
total is predicted to increase to more than
eight million in 2020 (Table 4.2). Thus current
cigarette smoking will cause about
450 million deaths worldwide in the next
50 years. Accordingly, smoking is recognized
as the most preventable cause of
death of humankind. Apart from lung and
several other cancers, respiratory heart
disease, chronic obstructive lung disease,
stroke, pneumonia, aortic aneurysm and
ischaemic heart disease are caused by
smoking and are, to that extent, preventable,
as are a range of non-fatal diseases
(Table 4.3) [1-3].
128 Prevention and screening
Attributable risk and years of life
potentially saved
Apart from knowing the diseases caused
by tobacco, increasingly definitive estimates
may now be made of the number of
lives lost and the extent to which those
lives were shortened. For a time, knowledge
of attributable risk and years of life
lost was restricted to quite specific populations:
the British doctors constituting the
cohort established by Doll and Hill in 1951
and monitored thereafter [2] and the
cohort of volunteers from the American
Cancer Society [4]. Extrapolation from
these relatively limited databases to, in
some instances, the population of the
whole world was inappropriate because,
despite validity of the respective studies,
the populations involved were predominantly
male white upper class Western
populations. Although this selection of the
population may not invalidate establishing
the list of diseases linked to use of tobacco,
extrapolation is more uncertain in relation
to quantitation of risk. The key quantities
that need to be measured include the
relative risk (measuring how much more
frequent the disease is in tobacco smokers
than in non-smokers) and the attributable
risk in the total population (measuring the
proportion of people suffering from the
disease in the population whose disease
may be attributed to smoking). Granted
the limitations already noted, follow-up of
the British doctors for 40 years [2] indicates
that one smoker out of three died
from a smoking-related illness, losing on
average 7.5 years of life (Fig. 4.1). It should
be noted that the outlook for smokers
worsens the longer the follow-up lasts.
Thus, based on the first 20 years of the
study, the estimate was five years of life
lost, but the period became 7.5 years when
the result for the last 20 years were added.
Most probably the final estimate will be
close to ten years, with perhaps the death
of one in two smokers being attributable to
the habit. The impact of smoking on survival
is dose-dependent; smokers of 25 or
more cigarettes per day have a survival of
Smoking significantly reduces overall survival.
British Doctors Study. Estimates based on
age-specific death rates for the entire 40-year
period. [2]
Fig. 4.2 Lung cancer mortality among men in
Canada and England, late 1980s, by social class.
only about 50% at around the age of 70
years, whereas 80% of non-smokers are
still alive.
World estimates for mortality caused by all
diseases linked to tobacco have been produced
[5] (Table 4.1). For the present, the
most affected regions of the world remain