Tobacco and Public Health - TCSC Indonesia

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SMOKING AND STOMACH CANCER (B)
Cessation of smoking affected the risk of cancer of the stomach. In the populationbased
case–control study from Sweden which included 338 cases of stomach cancer
and 678 community controls (Hansson et al. 1994), there was a statistically significant
association between number of years since quitting and the risk of stomach cancer
(P for trend = 0.02). In the study of De Stefani et al. (1998) relative risk of stomach
cancer among men who gave up smoking 10–14 years ago was 1.0 (95% CI 0.5–2.1),
while in those who gave up smoking 1–4 years ago relative risk was 2.4 (95%
CI 1.3–3.6), and in current smokers was 2.6 (95% CI 1.6–4.1). In the study reported by
De Stefani et al. in 1990, quitting for more than 10 years resulted in the decrease of
relative risk (RR = 0.6, 95% CI 0.3–1.0) in comparison with individuals who gave up
smoking 1–4 years ago (P for trend = 0.028).
Several case–control studies presented results separately for gastric cardia (or for adenocarcinoma
of distal oesophagus and gastric cardia) and distal stomach (Wu-Williams
et al. 1990; Kabat et al. 1993; Zhang et al. 1996; Gammond et al. 1997; De Stefani et al.
1998; Ye et al. 1999; Zaridze et al. 2000; Wu et al. 2001). In all these studies effects of
smoking on the risk have been seen for cancers of both sites. In some studies association
was somewhat stronger for distal stomach (Wu-Williams et al. 1990; Zhang et al. 1996;
Wu et al. 2001), in others with cancer of the gastric cardia (Kabat et al. 1993; Zaridze et al.
2000). Dose–response relationship was observed between number of cigarettes smoked
per day, duration of smoking, pack-years of smoking, age started smoking, and the risk
of cancer of the gastric cardia (Zhang et al. 1996; Gammon et al. 1997; De Stefani et al.
1998; Ye et al. 1999; Zaridze et al. 2000; Wu et al. 2001) and distal stomach (Gammon
et al. 1997; De Stefani et al. 1998; Zheng et al. 1996; Wu et al. 2001). Case–control study
from Sweden reported similar trends in relative risk of stomach cancer related to number
of cigarettes smoked per day—for cancer of the distal stomach (P for trend = 0.005) and
gastric cardia (P for trend = 0.04), duration of smoking—for cancer of the distal stomach
(P for trend = 0.002) and gastric cardia (P for trend = 0.03).
Smoking cessation significantly decreased the risk of cancer of gastric cardia. In a
population-based case–control study reported from Sweden which included 262 cases
of cancer of gastric cardia and 820 community controls, the increase in numbers of
years since smoking cessation was associated with statistically significant decrease in
the risk (P for trend < 0.0001). Those individuals who gave up smoking for more than
25 years had relative risk of 1.9 (95% CI 1.1–3.1), while those who quit 0–2 years ago
had relative risk of 4.2 (95% CI 2.8–6.4) (Lagergren et al. 2000). Similar trend was
observed by Wu et al. (2001), both for cancer of gastric cardia (P for trend < 0.0002)
and cancer of the distal stomach (P for trend < 0.002).
Significant association between smoking and risk persisted when relative risks were
computed separately for intestinal and diffuse types of stomach cancer (Kato et al.
1990; Ye et al. 1999).
Number of cases of stomach cancer in women was generally small and the increases
in risks associated with smoking were less than for men and statistically not significant