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Review
. 2013 Dec 14;19(46):8780-8.
doi: 10.3748/wjg.v19.i46.8780.

Smoking, alcohol consumption, and the risk of extrahepatic cholangiocarcinoma: a meta-analysis

Xiao-Hua Ye  1 , Jia-Ping Huai  1 , Jin Ding  1 , Yan-Ping Chen  1 , Xue-Cheng Sun  1
Affiliations
Review

Smoking, alcohol consumption, and the risk of extrahepatic cholangiocarcinoma: a meta-analysis

Xiao-Hua Ye et al. World J Gastroenterol. .

Abstract

Aim: To assess the association between smoking and alcohol consumption and extrahepatic cholangiocarcinoma (ECC) through a meta-analysis of clinical observational studies.

Methods: A literature search was conducted using Embase and MEDLINE databases from inception to 31 May 2013 without language limitations, and by manually searching the references of retrieved articles. Case-control and cohort studies that investigated the association between smoking or alcohol consumption and ECC were included. The quality of these studies was assessed using the Newcastle-Ottawa quality assessment scale. Summary relative risks and corresponding 95%CI were calculated using a random-effects model. Publication bias was assessed by Begg's funnel plot and Egger's test.

Results: A total of 12 eligible articles (11 case-control studies and one cohort study) were included in this meta-analysis. Eleven studies reported the association between smoking and ECC. Pooled analysis indicated that smokers had an increased risk of ECC development as compared with non-smokers (summary RR = 1.23; 95%CI: 1.01-1.50). This correlation was present in population-based studies (n = 5; summary RR = 1.47; 95%CI: 1.06-2.05) but not in hospital-based studies (n = 6; summary RR = 1.10; 95%CI: 0.88-1.37) and in non-Asian regions (n = 7; summary RR = 1.39; 95%CI: 1.03-1.87) but not in Asia (n = 4; summary RR = 1.08; 95%CI: 0.85-1.38). Seven studies reported an association between consuming alcohol and ECC. Pooled analysis indicated that alcohol drinkers had a similar risk of ECC development as did individuals who did not drink alcohol (summary RR = 1.09; 95%CI: 0.87-1.37). There was moderate heterogeneity among the studies and no evidence of publication bias.

Conclusion: Smoking is associated with an increased risk of ECC, but alcohol consumption is not. Further population-based studies, particularly cohort studies, are warranted to enable definitive conclusions.

Keywords: Alcohol consumption; Extrahepatic cholangiocarcinoma; Meta-analysis; Relative risk; Smoking.

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Figures

Figure 1
Figure 1
Flow chart of the study selection.
Figure 2
Figure 2
Relative risk of extrahepatic cholangiocarcinoma. A: Smokers as compared with non-smokers in population- and hospital-based case-control studies; B: Alcohol drinkers as compared with non-alcohol drinkers in case-control and cohort studies.
Figure 3
Figure 3
A Begg’s funnel plot with pseudo 95% confidence limits showing the symmetrical distribution of included studies. This indicates that there was no publication bias.
Figure 4
Figure 4
Influence of each individual study on the relative risks of extrahepatic cholangiocarcinoma in smokers as compared with non-smokers. Data show the RR (open circle) and 95%CI (dashed horizontal line) when the study named on the left was omitted. Random-effects estimates (exponential form) were used. RR: Relative risk.
Figure 5
Figure 5
Proposed mechanisms by which smoking may be associated with the formation of extrahepatic cholangiocarcinoma.
See this image and copyright information in PMC

References

    1. Welzel TM, McGlynn KA, Hsing AW, O’Brien TR, Pfeiffer RM. Impact of classification of hilar cholangiocarcinomas (Klatskin tumors) on the incidence of intra- and extrahepatic cholangiocarcinoma in the United States. J Natl Cancer Inst. 2006;98:873–875. - PubMed
    1. Khan SA, Emadossadaty S, Ladep NG, Thomas HC, Elliott P, Taylor-Robinson SD, Toledano MB. Rising trends in cholangiocarcinoma: is the ICD classification system misleading us? J Hepatol. 2012;56:848–854. - PubMed
    1. Shaib YH, Davila JA, McGlynn K, El-Serag HB. Rising incidence of intrahepatic cholangiocarcinoma in the United States: a true increase? J Hepatol. 2004;40:472–477. - PubMed
    1. Tyson GL, El-Serag HB. Risk factors for cholangiocarcinoma. Hepatology. 2011;54:173–184. - PMC - PubMed
    1. Wood R, Brewster DH, Fraser LA, Brown H, Hayes PC, Garden OJ. Do increases in mortality from intrahepatic cholangiocarcinoma reflect a genuine increase in risk? Insights from cancer registry data in Scotland. Eur J Cancer. 2003;39:2087–2092. - PubMed