Secondhand Smoking, 4-Aminobiphenyl, and Bladder Cancer: Two Meta-analyses

Abstract

Objective: 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. Methods: 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). Results: 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 randomeffects 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. Conclusion: 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.

A Case–Control Study of Smoking and Bladder Cancer Risk: Emergent Patterns Over Time

“…Only a few studies have examined ETS as a risk factor for bladder cancer, with some reporting positive associations ( 13 , 14 , 45 ) and others reporting null results ( 8 , 17 , 46 , 47 ) including a recent meta-analysis ( 48 ). We observed no statistically signifi cant association between ETS exposure and bladder cancer risk.…”

Falling bladder cancer incidence from 1990 to 2009 is not producing universal mortality improvements

“…Currently available evidence suggests no link between passive smoking and bladder cancer. 11 Lower incidence but more advanced disease and higher relative mortality from bladder cancer in females are consistent worldwide. [12][13][14][15][16] Lower female incidence may result from less smoking and industrial occupational exposure; nonetheless female-dominated occupations such as hairdressing and increases in young female smokers in deprived populations may explain slower falls.…”

Sex differences in bladder cancer outcomes among smokers with advanced bladder cancer

“…A dose-depended risk increase has been reported among patients with longer smoking duration and higher amount of tobacco exposure [ 1 -3 ] . On the other hand, according to current knowledge, second-hand smoke is not associated with a signifi cant increase in the risk of BC [ 4 ] . Finally, smoking cessation is known to be associated with a decreased risk of BC, although the decrease in risk appears to be markedly slower than reported in the case of lung cancer and the BC risk of former smokers never reaches the level of non-smokers [ 3 ] .…”