Tobacco and Public Health - TCSC Indonesia

lood levels among current smokers, while the other two (Key et al. 1991; Law et al.
1997) found no clear differences according to smoking status.
Studies of cigarette smoking and urinary hormone levels
Seven studies have examined cigarette smoking and urinary estrogen levels
(MacMahon et al. 1982; Michnovicz et al. 1986, 1988; Trichopoulos et al. 1987; Berta
et al. 1992; Key et al. 1996; Berstein et al. 2000) (Table 31.6), and of these, three found
no major differences according to smoking status (Trichopoulos et al. 1987;
Michnovicz et al. 1988; Berta et al. 1992). The remaining four studies each showed
lower urinary estriol levels among smokers than nonsmokers, but mixed results for
urinary estrone and estradiol (MacMahon et al. 1982; Michnovicz et al. 1986; Key et al.
1996; Berstein et al. 2000). The results of two of these studies (Michnovicz et al. 1988;
Berstein et al. 2000) showed lower levels of 2-hydroxyestrone among smokers than
nonsmokers.
Studies of cigarette smoking and age at menopause
PAUL D. TERRY ET AL. 537
Age at natural menopause varies substantially under the influence of genetic and
environmental factors (McKinlay 1996). A relatively early age at menopause has been
associated with reduced risk of endometrial cancer (Kelsey et al. 1982; Baron 1984;
Baron et al. 1990; Akhmedkhanov et al. 2001). For example, a one year decrease in age
at menopause has been associated approximately with a 7 per cent decrease in risk
(Kelsey et al. 1982). In this regard, it has been proposed that cigarette smoking decreases
the age at natural menopause (Baron et al. 1990), and might reduce endometrial cancer
risk through reduced exposure to endogenous estrogens. At least 19 studies have examined
the association between cigarette smoking and age at natural menopause
(Hammond 1961; Daniell 1976, 1978; Bailey et al. 1977; Jick and Porter 1977;
McNamara et al. 1978; Lindquist and Bengtsson 1979; van Keep et al. 1979; Kaufman
et al. 1980; Adena and Gallagher 1982; Andersen et al. 1982; Willett et al. 1983;
McKinlay et al. 1985; Brinton et al. 1986; Hiatt and Fireman 1986; Stanford et al. 1987;
Brownson et al. 1988; Chu et al. 1990; Field et al. 1992) (Table 31.7). In these studies,
differences in age at menopause between smokers and nonsmokers were measured in
terms of differences in means (Daniell 1976, 1978; McNamara 1978; Kaufman et al.
1980; Adena and Gallagher 1982; Hiatt and Fireman 1986; Field et al. 1992; Weiderpass
et al. 1999), medians (McKinlay et al. 1985; Brinton et al. 1986; Stanford et al. 1987;
Brownson et al. 1988; Chu et al. 1990), or the percentage of women who reached
menopause by a certain age (Hammond 1961; Bailey et al. 1977; Jick and Porter 1977;
Lindquist and Bengtsson 1979; van Keep et al. 1979; Andersen et al. 1982; Willett et al.
1983) (these latter studies are not shown in Table 31.7). These studies have shown that,
on average, smokers have menopause 1–1.5 years earlier than nonsmokers. There are
no clear differences in the results of studies that adjusted estimates for obesity (and
other covariates) compared to those that did not.