Tobacco and Public Health - TCSC Indonesia

TONGZHANG ZHENG ET AL. 421
decline in the concentration of several important carcinogens (Brunnemann and
Hoffmann 1993).
Since the levels of carcinogens in smokeless tobacco vary considerably from country
to country, studies of different populations have reached very different conclusions.
In the following, we will review the studies based on the country of origin of the study.
Studies in Sweden: Approximately, 15–20% of adult males use moist snuff in Sweden
(Lewin et al. 1997). In fact, Sweden was the world’s largest per capita consumer of
smokeless tobacco throughout the twentieth century (Nordgren and Ramstrom 1990).
Although an early study by Wynder et al. (1957) suggested an increased risk of oral
cancer among snuff users, more recent studies from Sweden have found no relationship
between use of local snuff and oral cancer risk. The population-based case–
control study by Lewin et al. (1997) found no increased risk of head and neck cancer
with ever using oral snuff. Age started using snuff, total number of years of using snuff,
and total amount of snuff used in a lifetime all had little or no impact on the risk of
head and neck cancer in this study.
Another recent case–control study by Schildt et al. (1998) also showed no increased
risk of oral cancer among current snuff users regardless of tobacco smoking habits.
Lifetime consumption of snuff also showed no increased risk. While ex-snuff users
were found to have an increased risk, but the risk was seen only among those who were
also active tobacco smokers. Users of chewing tobacco in this study (5 cases and 8 controls)
also did not show an increased risk of oral cancer (OR = 0.6, 95% CI 0.2–2.2).
An early retrospective follow-up study of 200 000 male snuff users in Sweden also
failed to find a significantly increased risk of oral cancer (Axell et al. 1978). Ecological
data from Sweden do not support an association between use of local snuff and oral
cancer risk in this population (Lewin et al. 1997). Specifically, Geographic areas where
consumption of oral snuff is highest, the incidence rate of head and neck cancers is
low, and, areas with low consumption of snuff, the incidence for cancer of the head and
neck is the highest.
Studies in the US: In the US, while the national prevalence rate of smokeless tobacco
use is low (about 5% for regular use), the rates are high in some parts of the country.
In North Carolina, for example, Winn et al. (1981) reported that 46% of the oral
cancer cases and 30% of the controls were snuff users. Epidemiological studies from
the US have generally indicated an increased risk of oral cancer associated with the use
of oral snuff.
The most conclusive study was conducted in North Carolina by Winn et al. (1981).
The study interviewed 232 female cases and 410 female controls, and found that
smokeless tobacco use was a potent risk factor for oral cancer in this population.
Among white women without a smoking habit, the oral and pharyngeal cancer cases
were 4.2 times (95% CI 2.6–6.7) more likely to have used smokeless tobacco than were
controls. Among women with cancer in the cheek or gums, where tissues come in