Van Hemelrijck Mieke J J, Michaud Dominique S, Connolly Gregory N, Kabir Zubair
Division of Cancer Studies, King's College London, Research Oncology, London SE1 9RT, UK.
Cancer Epidemiol Biomarkers Prev. 2009 Apr;18(4):1312-20. doi: 10.1158/1055-9965.EPI-08-0613. Epub 2009 Mar 31.
To quantify the relation between secondhand smoking (SHS) and levels of 4-aminobiphenyl (4-ABP; in urine or blood) and SHS and bladder cancer risk in nonsmokers.
PubMed and Embase were searched (search terms to represent SHS, bladder cancer, and 4-ABP) to conduct two meta-analyses. Information about gender and age of participants, mean 4-ABP level for each SHS category, number of subjects, relative risk or odds ratio and 95% confidence intervals (95% CI) in each SHS category, and covariates for which adjustment was made was extracted based on predefined inclusion and exclusion criteria. Random-effects analyses were done using STATA (version 9).
A 118 studies were reviewed for information on SHS and 4-ABP (31 studies) and SHS and bladder cancer risk (87 studies). Of those, seven case-control studies were included for analysis of SHS and 4-ABP and eight articles (three cohort and five case-control studies) for SHS and bladder cancer risk. A random-effects model found a pooled standardized mean difference of 1.47 (95% CI, 0.23-2.71), indicating higher levels of 4-ABP among nonsmokers exposed to SHS. A random-effects model showed no evidence for an association between SHS and bladder cancer risk (relative risk, 0.99; 95% CI, 0.86-1.14), comparing nonsmokers with and without SHS exposure.
Higher levels of 4-ABP were significantly associated with SHS exposure, which is consistent with earlier findings for 4-ABP levels in sidestream smoke. The current evidence indicates that there is no association between SHS and bladder cancer, but future studies that address methodologic limitations are needed to further clarify this important question.
量化二手烟（SHS）与4-氨基联苯（4-ABP；尿液或血液中的含量）水平之间的关系，以及二手烟与非吸烟者膀胱癌风险之间的关系。
检索PubMed和Embase（代表二手烟、膀胱癌和4-ABP的检索词）以进行两项荟萃分析。根据预先定义的纳入和排除标准，提取有关参与者的性别和年龄、每个二手烟类别中的4-ABP平均水平、受试者数量、每个二手烟类别中的相对风险或比值比以及95%置信区间（95%CI），以及进行调整的协变量信息。使用STATA（版本9）进行随机效应分析。
对118项研究进行了综述，以获取有关二手烟与4-ABP（31项研究）以及二手烟与膀胱癌风险（87项研究）的信息。其中，纳入了7项病例对照研究用于分析二手烟与4-ABP，8篇文章（3项队列研究和5项病例对照研究）用于分析二手烟与膀胱癌风险。随机效应模型发现合并标准化均差为1.47（95%CI，0.23 - 2.71），表明接触二手烟的非吸烟者中4-ABP水平更高。随机效应模型显示，比较有和没有接触二手烟的非吸烟者，没有证据表明二手烟与膀胱癌风险之间存在关联（相对风险，0.99；�5%CI，0.86 - 1.14）。
4-ABP水平升高与二手烟暴露显著相关，这与侧流烟雾中4-ABP水平的早期研究结果一致。目前的证据表明二手烟与膀胱癌之间没有关联，但需要未来研究解决方法学上的局限性，以进一步阐明这个重要问题。
