Tobacco and Public Health - TCSC Indonesia

coefficients from the data in Table 29.1 are + 0.85 (p < 0.001) and + 0.81 (p < 0.05),
respectively. Compatibility of the empirical evidence with the working hypothesis of
information bias does not, of course, establish the validity of this hypothesis, but it
lends credibility to it.
Conclusion
DIMITRIOS TRICHOPOULOS AND ARETI LAGIOU 507
Table 29.1 Odds ratios (and 95 per cent confidence intervals) for breast cancer among passive
smokers and among active smokers in comparison to neither-active-nor-passive smokers.
Results of 11 case–control studies*
Case–control studies Adjusted OR (95 per cent CI)
Passive smoking Active smoking
Wells 1992 (Sandler) 1.6 (0.8−3.4) 1.2 (0.6−2.5)
Morabia et al. 1996 2.3 (1.5−3.7) 2.5 (1.6−3.8)**
van Leeuwen et al. 1997 (Rookus) 1.2 (0.8−1.7) 1.2 (0.8−1.6)
Wells 1998 (Smith) 1.6 (0.8−3.1) 2.0 (0.98−4.1)
Lash and Aschengrau 1999 2.0 (1.1−3.7) 2.0 (1.1−3.6)
Zhao et al. 1999 2.5 (1.7−3.8) 3.5 (1.3−9.3)
Millikan et al. 1998; Marcus et al. 2000 1.3 (0.9−1.9) 1.1 (0.8−1.6)**
Delfino et al. 2000 1.9 (0.8–4.3) 1.4 (0.8–2.7)**
Johnson et al. 2000—pre-menopausal 2.3 (1.2−4.6) 2.3 (1.2−4.5)
Johnson et al. 2000—post-menopausal 1.2 (0.8−1.8) 1.5 (1.0−2.3)
Chang-Claude et al. 2001 1.5 (1.0−2.3) 1.4 (0.9−2.2)
*Modified from: Morabia 2002.
**Crude OR.
There is little evidence that passive smoking increases the risk of breast cancer,
although one cannot reject this possibility. The problem is the more general one of
distinguishing between a null association from a weakly positive one, or, indeed, a
weakly negative one, on the basis of epidemiological evidence alone.
With respect to active smoking, the overall epidemiological evidence is also weak.
There are findings, however, suggestive of interaction of this exposure with the differentiation
status of the mammary gland, as reflected by age at exposure and parity, and
these findings cannot be explained by simple forms of information bias. There are also
reports that active smoking affects selectively hormone receptor negative tumours, and
that it modifies the spectrum of p53 mutations in breast tumours. These results may
reflect chance or selective reporting, but, if they were to be replicated and further supported
by epidemiological results, they could mean that active smoking affects breast