Revisiting the Association between Environmental Tobacco Smoke Exposure and Lung Cancer Risk

Abstract

Hackshaw et al. [BMJ 1997;315:980-988] estimated that, in non-smoking women, lung cancer risk rises 23% (95% Cl 14-32%) per 10 cigarettes per day smoked by the hus band and 11% (95% Cl 4-17%) per 10 years exposure. Although we reproduced these estimates approximately, use of later and more appropriate data gave lower val ues : 10% (95% Cl 5-15%) per 10 cigarettes per day and 7% (95% Cl 4-11%) per 10 years. Among the reasons Hackshaw et al. [1997] reported higher risks are failure to consider studies reporting results only as exposed/unex posed and substantial overweighting of results from one study. Extended analysis revealed that a linear model fits the data as well as the exponential model of Hackshaw et al. [1997] in the observed range, but yields more plausi ble risk estimates at higher doses. In this paper, we also introduce a method to convert dose-response data, re ported only as a set of correlated risk estimates and con fidence intervals, into a form amenable to dose-response summary analyses.