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my personal edition > lung cancer > news
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DGReview
Longer Second-Hand Smoke Exposure Increases Lung Cancer Risk in Never-Smokers
International Journal of Cancer
12/18/2003
By Deanna M Green, PhD
Exposure to second-hand smoke from spousal, workplace and social sources confers a 22% increased risk of lung cancer in people who never smoked, according to a pooled analysis of European and American cohorts. Moreover, those with the longest exposure had an increased risk of 32%.
Several studies have attempted to evaluate the association between exposure to second-hand smoke and the risk of lung cancer in lifelong nonsmokers. While study-specific results differ, a consistent increased risk of lung cancer has been found with second-hand smoke and spousal smoking has been identified as a significant exposure source.
Questions still remain regarding the actual level of risk associated with increasing exposure and whether other potential sources of exposure exist, including social and workplace settings.
Paul Brennan, PhD, with the International Agency for Research on Cancer, Lyon, France, and colleagues evaluated the risk of lung cancer due to second-hand smoke exposure in non-smokers.
Data were analysed from 2 large case-controlled studies that included 1,263 lung cancer patients who never smoked and 2,740 population and hospital-matched controls. Odds ratios (OR) were calculated based on incidence and duration of exposure to second-hand smoke from spouse, workplace and social sources.
Overall, the OR for lung cancer associated with any exposure to second-hand smoke was 1.22, with the greatest health risk in patients with the highest exposure (OR 1.32).
Similar results were seen with each exposure source. Specifically, the OR determined for exposure to spousal tobacco smoke was 1.18, for workplace exposure 1.13, and for social exposure 1.17. Patients with more than 31, 21, and 20 years of exposure, respectively, were at the greatest risk (OR 1.23-1.26).
The dose-response relationship was observed for all sources, yet only reached statistical significance for workplace (P = .01) and social (P = .02) exposure.
Interestingly, lung cancer patients in the group exposed to the most social setting exposure had a higher risk of small and squamous cell carcinoma (OR = 1.54) than adenocarcinoma (OR = 1.26).
Further analysis revealed that similar results were obtained with and without inclusion of potential confounders, such as employment in high-risk occupations, education level and vegetable consumption. The authors note that this "confirm[s] the lack of any apparent confounding."
The authors conclude that this study "provides firm evidence for a dose-response relationship between lung cancer risk and duration of exposure to second-hand smoke for the 3 main sources of exposure: spousal, workplace and social." They add that this study "emphasizes the importance of protecting nonsmokers from second-hand smoke."
Int J Cancer Published Online: 10 Dec 2003.
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