Background and objective: Studies of passive smoking exposure in China however are of particular interest, because of the high lung cancer rate in people who are mostly non-smokers. The aim of this study is to explore the relationship between passive smoking and lung cancer among non-smoking Chinese.
Methods: By searching Medline, PubMed, CENTRAL (the Cochrane central register of controlled trials), CBM, CNKI and VIP, et al, we collected both domestic and overseas published documents between 1987 and 2007 on passive smoking and lung cancer among non-smoking Chinese. Random or fixed effect models were applied to conduct meta-analysis on the case control study results, and the combined odds ratio (OR) and the 95% confidence interval (CI) were calculated as well.
Results: Sixteen documents were included into the combined analysis, which indicated that there was statistical significance between passive smoking and lung cancer (OR = 1.13, 95% CI: 1.05-1.21, P = 0.001). It was significant of lung cancer among non-smoking subjects associated with amount of tobacco passively smoked more than 20 cigarettes daily, with life period in adulthood passive smoking exposure, with gender female, and with exposure to workplace. The P value, OR and 95% CI were P = 0.0003, OR = 1.78, 95% CI: 1.30-2.43; P = 0.0001, OR = 1.50, 95% CI: 1.23-1.83; P = 0.000 7, OR = 1.50, 95% CI: 1.19-1.90; P < 0.0001, OR = 1.41, 95% CI: 1.19-1.66; respectively. And there was no significant difference between passive smoking and lung cancer with amount of tobacco passively smoked within 20 cigarettes daily, with life period in childhood passive smoking exposure, with gender male and with exposure to spouse and parents.
Conclusion: Passive smoking is an important risk factor of lung cancer among non-smoking Chinese, and for non-smoking women who expose to environment tobacco smoke in a long period of time have a close relationship with lung cancer risk.
方法: 通过计算机检索Medline、PubMed、CENTRAL（the Cochrane central register of controlled trials）、中国生物医学文献数据库系统（CBM）、中国期刊全文数据库（CNKI）、中文科技期刊全文数据库（VIP）等收集国内外1987年-2007年间公开发表的关于中国非吸烟人群被动吸烟与肺癌的研究文献，应用统计软件Stata 11.0进行数据分析，计算其合并优势比（odds ratio, OR）和95%置信区间（confidence interval, CI）。采用Begg和Egger法对发表偏倚进行量化检测。
结果: 纳入分析的文章共有16篇，合并分析结果表明：中国非吸烟人群被动吸烟与肺癌的关系有统计学意义（OR=1.13, 95%CI: 1.05-1.21, P=0.001）。每日被动吸烟≥20支、成年时期被动吸烟、非吸烟女性被动吸烟、被动吸烟暴露于工作环境等与肺癌的发生关系具有统计学意义，P值、OR值及95%CI分别为：P=0.000 3、OR=1.78、95%CI: 1.30-2.43，P=0.000 1、OR=1.50、95%CI: 1.23-1.83，P=0.000 7、OR=1.50、95%CI: 1.19-1.90，P < 0.000 1、OR=1.41、95%CI: 1.19-1.66。