Tobacco and Public Health - TCSC Indonesia

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(Kato et al. 1990; Ji et al. 1996; Zaridze et al. 2000). However in the studies where sufficient
number of cases of stomach cancer in women were included the size of relative
risks were comparable with relative risk in men. For example in the study from Japan
which included 995 cases of stomach cancer of which 344 were women showed statistically
significant increase in relative risk among current smoking women (RR = 1.74,
95% CI 1.28–2.36). Risk estimates were higher in women in the age of 60 years or
more (RR = 1.99, 95% CI 1.24–3.21) (Innoue et al. 1994). In the study of Kabat et al.
(1993) current smoking women were at increased risk of adenocarcinoma of distal
oesophagus and the gastric cardia (RR = 4.8, 95% CI 1.7–5.4) and cancer of the distal
stomach (RR = 4.8, 95% CI 1.9–11.9). Highest relative risks were for those women who
smoked for more than 21 years. Ever smoking Polish women were also at increased risk
of stomach cancer (RR = 1.8, 95% CI 1.1–3.0) (Chow et al. 1999). Risk was increased
in current smokers (RR = 1.8, 95% CI 1.0–3.3), as well as in former smokers (RR = 1.8,
95% CI 0.9–3.7).
Of special interest is the mortality-based case–control study carried out in China
(Liu et al. 1998). In this study 27 710 deaths (20 195 men and 7515 women) from
stomach cancer were identified. The reference group included individuals who died
from causes not related to smoking. Information on smoking habit was obtained from
proxy interviews. It has been shown that in men smoking increases the risk of stomach
cancer by 30%, while current smoking in women was associated with only 17%
increase in the risk. According to this study 18% of death from stomach cancer in
Chinese men and only 1.7% in women could be attributed to smoking. These figures
reflect present not very high smoking rates in Chinese, specially in Chinese women,
which unfortunately inevitably will rise. Similar trends will be seen in other countries,
where smoking epidemics in women have not yet reached its maximum. Increase in
smoking rates in women will be followed by rise of smoking-related relative risks of
cancers, including stomach cancer and proportion of death attributable to smoking.
Diet and alcohol consumption, all associated with the risk of stomach cancer could
be major confounding factors of the effect of smoking on the risk of cancer of this site
(World Cancer Research Fund 1997; Zaridze et al. 2000). However, adjustment for
alcohol drinking (De Stefani et al. 1990; You and Hsieh 1991; Kabat et al. 1993; Ji et al.
1996; Simieticky et al. 1996; Zhang et al. 1996; Gammon et al. 1997; De Stefani et al.
1998; Innoue et al. 1999; Ye et al. 1999; Lagergren et al. 2000; Zaridze et al. 2000), as
well as for consumption of fresh fruits and vegetables (De Stefani et al. 1990; You and
Hsieh 1991; Inoue et al. 1994; Semiaticki et al. 1995; Gajalakshmi and Shanta 1996;
De Stefani et al. 1998; Innoue et al. 1999; Lagergren et al. 2000), did not materially
effect the risk estimates associated with smoking.
Positive association between smoking and the risk of stomach cancer could be confounded
by the effect of H. pylori infection status. A large body of evidence supports a
causative role for H. pylori in stomach cancer. In 1994 IARC recognized H. pylori as a
class 1 human carcinogen (IARC 1994).