Tobacco and Public Health - TCSC Indonesia

384
SMOKING AND CANCER OF THE OESOPHAGUS
of oesophageal cancer’ (IARC 1986). Several other studies published since have
further confirmed this association, and in the evaluation on the carcinogenicity of
tobacco done in 2002 the IARC concluded that ‘tobacco smoking is causally associated
with cancer of the oesophagus’ (IARC 2002).
This conclusion relies on overwhelming evidence, derived from studies conducted
in different areas of the world and with different designs, that—with only very rare
exceptions—found higher risks of OC in smokers. Table 22.1 shows the results of
selected case–control studies of OC. As it will be discussed later, alcohol consumption is
an important confounder/effect modifier of the relation between smoking and risk of
SCCO. Thus, only studies that present alcohol-adjusted estimates are included in the
table. In most studies, the risk of smokers was 2–5 times that of never smokers, and the
risk of former smokers was intermediate between the two. The causality of the association
is further supported by the fact that the risk of oesophageal cancer increases with
increasing daily dose and with duration of the habit in almost all studies.
Type of cigarettes. De Stefani and colleagues (1993) noted that the OR of OC were
higher in studies conducted in populations smoking mainly black tobacco, as compared
to those in populations smoking predominantly blond tobacco. Consistently,
studies presenting ORs separately for smokers of blond and black tobacco cigarettes
tended to find higher risks in black tobacco smokers. Compared to blond tobacco
cigarette smoker, the risk of OC of black tobacco cigarette smokers was 2.6 and 3.6 in
two studies from Uruguay (De Stefani et al. 1993). Smokers of hand-rolled cigarettes
also tend to have higher risks of OC than smokers of commercial cigarettes (Tuyns and
Esteve 1983; De Stefani et al. 1993; Hu et al. 1994; Launoy et al. 2000). Also high-tar
cigarettes convey a higher risk of OC (La Vecchia et al. 1986).
Cigars and pipe smoking. Also cigar and pipe smokers have an increased risk of OC.
In the study by Wynder and Bross (1961) the OR of OC of cigarette smokers was 2.8,
compared to never smokers, that of cigar and pipe smokers was 6.0, and that of pipe
only smokers was 9.0. Other studies also found higher risks of OC in pipe smokers
compared to cigarette smokers (Tuyns and Esteve 1983; De Stefani et al. 1993). The
studies that analysed the risk of smokers of cigars only were generally based on small
numbers of cases, but they consistently found an increased risk of about fourfold for
ever cigar smokers (La Vecchia et al. 1998; Shanks and Burns 1998).
Interaction with alcohol. Alcohol is another well-established risk factor for OC, and
alcohol and tobacco act synergistically in magnifying the risk. Thus, in countries where
both habits are widespread, the effect of tobacco cannot be considered separately from
that of alcohol. Some studies have analysed how the joint exposure to alcohol and
tobacco influences the risk of OC.
Already in 1961 Wynder and Bross noted that both factors were independently
associated to oesophageal cancer risk. In 1977 Tuyns and colleagues published
the results of their case–control study on cancer of the oesophagus conducted in