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

Figure 1 Flow chart of the study selection.

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 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 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 Proposed mechanisms by which smoking may be associated with the formation of extrahepatic cholangiocarcinoma.