Tobacco and Public Health - TCSC Indonesia

390
SMOKING AND CANCER OF THE OESOPHAGUS
Ille-et-Vilaine, OC is a rare disease in non-smoking moderate drinkers. Further studies
have confirmed that the risk of OC in heavy smokers and drinkers, compared to nonor
light smokers and drinkers, is of that order of magnitude (Segal et al. 1988; Zambon
et al. 2000).
Tuyns and colleagues further noted that the risks appeared to follow a multiplicative
model, i.e. the risk for subjects simultaneously exposed to both alcohol and tobacco is
the product of the risks of those exposed to only one factor. Breslow and Day (1980)
have modeled in detail the relation between alcohol and tobacco consumption and risk
of cancer of the oesophagus, using the Ille-et-Vilaine data. Also in many other studies,
a multiplicative model appeared to describe the joint ORs for alcohol and tobacco
satisfactorily (Zambon et al. 2000). Moreover, smoking may interact in a multiplicative
way also with other risk factors, e.g. dietary factors.
Although oesophageal cancer is less frequent in women than in men in many
countries, and most of the studies were based only or prevalently on men, smoking and
drinking are also risk factors for women (Gallus et al. 2001).
Tobacco in alcohol non-drinkers. The few studies that investigated the effect of smoking
in alcohol non-drinkers were generally based on small numbers of cases. Nevertheless,
they have consistently reported that smoking is a risk factor for OC also in absence of
alcohol consumption (Tuyns 1983; La Vecchia and Negri 1989; Tavani et al. 1996).
These studies included both never and former drinkers. In a case–control study
conducted in Hong Kong among never drinkers, smoking was still a risk factor for OC,
and the OR for heavy smokers was increased 10-fold compared to never smokers
(Cheng et al. 1995).
Smoking and drinking cessation. Several studies have shown that the risk is lower in
ex-smokers than in current smokers, and declines steeply with time since stopping smoking
(Brown et al. 1988; Yu et al. 1988; La Vecchia et al. 1990; Castellsagué et al. 1999a).
A study conducted in Italy and Switzerland provided convincing evidence that stopping
consumption of both alcohol and tobacco leads to a substantial reduction of OC
risk (Bosetti et al. 2000). After 10 or more years since stopping both habits the risk was
only about one-tenth of that of current smokers and drinkers (Fig. 22.2). Similar
results were found also in a combined analysis of five case–control studies conducted
in South America (Castellsagué et al. 2000).
Attributable risks. The proportion of cases of OC attributable to smoking, and to the
joint effect of alcohol and tobacco, varies widely between geographical areas. The
attributable fraction depends not only from the relative risk but also from the frequency
of the exposure in a population. Moreover, as shown above, the effect of smoking is
magnified by alcohol (and possibly other risk factors). Thus, even the same amount of
smoking may have a different impact in populations with different exposure to alcohol
or other factors. In North and South America and Europe, alcohol and tobacco explain
the vast majority of cases, particularly in men, where the disease is more frequent than